Yeah, other people have brought this up below, but I really think because of the subcultures a lot of tech-y/Grey Tribe/etc. people swim in, they not only overestimate the effects of sexlessness, but totally give bad reasons to explain the rise.
1.) A big thing pointed out that's a supposed reason is all the women who would've settle down with a nice guy like them is instead on Tinder, having sex with random dudes every other weekend. When the reality is this just isn't true. Obviously, if you already have the belief all women lie, these stats aren't going to speak to you, but when you look at GSS data (which is the gold standard of social science surveys and a zillion times better than the typical poll), the percentage of people w/ lots of sexual partners among people under 30 really hasn't changed (https://twitter.com/ryanburge/status/1302751344567242752/photo/1)
According to these stats, a larger percentage of the population under 30 had 10 or more partners over a period of 5 years in 1991 then in 2018. The actual reality, is the vast majority of people basically are quasi-monogamous, and continue to be, even if they aren't getting married and popping out kids.
Now, the other evidence is that the 20/80 rule is bunk, it's really a 20/60 rule, and more importantly, it's incredibly stable - as Lyman Stone, a social conservative pointed out in his article about this, " In reality, according to the GSS, the top 20% of the most sexually active never-married young men have about 50-60% of the sex. It’s about the same for women, and these shares are basically stable over time. Measuring the number of partners instead of sexual frequency, the top 20% most promiscuous men account for about 60% of male sexual partnerings, and the trend is, again, quite stable over time."
So, why do people believe the opposite? Culture, overreacting to subcultures where they live, and frankly, bad data.
On culture, what I'm talking about is TV shows that push the idea that young, single people have a lot of sexual partners. This isn't a new thing - Jerry Seinfeld had a new model as his date seemingly every week on his TV show, and obviously, if you have a TV show, an easy way to bring in a new short term character, and create conflict with existing characters it to have them dating.
In addition, things like social media give a false impression - I mean, if a woman or guy is at some EDM club, they must end up in somebodies bed at the end of the night, otherwise go to an EDM club, right? Again, being hyperbolic, but I actually think this is the logical leaps a lot of people jump too.
By subcultures, I mean, a lot of guys not having sex who complain a lot about not having sex, anecdotally, live in very urban places where more people likely are having a lot of sex. That 10% of people w/ 5+ partners in the past 5 years? Probably a decent chunk of that percentage live in NYC, Los Angeles, San Francisco, etc. As a result, people see a lot of people hooking up around them, and assume it's happening everywhere.
The other thing is Bad Data - or I guess, overanalyzing off questionable data in the first place. Even putting aside stuff like the 20/80 rule, people look at things like the famous OKCupid Blog Post or a few other things, and catastrophize based on that.
2.) So, what's to be done? I actually think a lot of what /u/2cimarafa said is largely on point. If you fail to be interested in women, and largely aren't around them, you're going to stumble and fail in the short and long term.
Also, what a lot of people miss is that actually, a lot of good looking people also happen to be charismatic, interesting, and intelligent. Now, whether some of those things follow-on from the attractiveness or vice versa is unknown, but the percentage of pure bimbos/himbos in society is actually fairly low.
As a side note, that's why high school movies of the 80's and early 90's seemed out of step, while going to high school in suburban Florida in the late 90's/early 00's - 1/2 the cheerleading squad and large portions of the various sports teams were in the same AP & Honor classes as me, and were perfectly friendly and even cool with almost everyone.
Getting back to my larger point, the good looking guy leaving with the cute girl at the bar might've gotten in the metaphorical door because he had nice cheekbones, but he got from his initial greeting to calling an Uber because he likely at least acted like he was interested, could be relatively charming, and wasn't an open asshole. As funny as it is, that SNL skit about hot dudes getting away with sexual harassment isn't actually true in the larger culture.
3.) Now, here's the thing - I admit, a lot of things women are interested in, I've got zero interested in, but the other reality, the opposite is true as well. The difference is, unlike some guys, the way I've been moderately successful (when I've tried, which is something else I'll talk about later) is that yes, I have weird, niche interests. I also have some interests that are cross-cultural in women and men, and I'm not completely closed off to thing women are interested in.
After all, somebody downthread complained about astrology and other things that women are interested in as completely valueless. That may be true but as somebody else pointed out, most people, attractive or unattractive, are pretty boring. The half-serious joke is that the only thing attractive women do is post on Instagram, go to brunch, etc. Well, ya' know what a lot of unattractive males do? Play the same video game every night, watch the same TV shows, and go to the same half a dozen places to eat.
Despite again, being painfully average of in reality, possibly below average, when I've cared, I've been decently successful dating because I actually put forth some effort, and I'm not a total weirdo or a total asshole. I honestly think a lot of people are in fact, kind of weird, and either don't know that, or they overreact to their own weirdness, and become assholes, but still don't understand why that's working for them either.
As was noted below, there are actually a lot of 'normie' women, including attractive ones who don't post Thirst Thraps on Instagram or even do much social media a normal guy would run into at all, because obviously, the Algorithim isn't showing most guys pictures of gardening or posts about female-centric books or whatever.
4.) So, what's actually happening culturally? Lyman Stone, a social conservative as I pointed out above, says most of the change is due to delaying in marriage lead to rising sexlessness, since even though there's plenty of jokes about the opposite, the actual reality is married people have more sex than single people, for obvious reasons.
I kind of buy that, but I also have another view that's more important than Tinder - even pre-COVID, people are less social in general, and more importantly, technology has led to a lot of 'Almost As Good As' alternatives to sex thanks to increased broadband.
This is for both genders - if you're a male, what's an actually better situation - going out with a woman you might be only mildly attracted too physically, but not attracted too mentally, having mediocre sex with eventually, and then dealing with either ghosting you or being entirely too attached to you or you can play a video game that keeps you entertained and enthralled for hours upon hours, and at the end of the night, watch high quality porn, either amateur or professional.
The opposite is also true for women - what sounds like a better time? Going out to get hit on by a bunch of guys you're not interested in or finally saying 'yes' to somebody on Tinder, having mediocre sex where you don't even have an orgasm, and then either dealing with the guy never calling you again or acting like you're basically married or watch an 8 hour marathon of Hallmark Christmas movies, and then either watch or read some erotica at the end of the night and actually get to have an orgasm?
I'm obviously being hyperbolic in both cases, but I do think the fact that for both genders, there's a combination of media + sexual alternatives that's almost as good as actual sex, is helping matters.
Now, the follow-up is OK, why are dudes having less sex than men? First, if you look at the various actual polling and studies, the percentages and delta between men and women differ pretty vastly depending on the data set you use, but in all of them, women are doing slightly better than men.
So, the reason for that, I think is pretty simple - the median young woman, even an introverted one, is far more social than the median young guy. They're also far more likely to be in mixed social company, and there you go.
5.) I also think it's really important that the Evil App's are not really the issue here. Tinder is just all the women who would've said no to you anyway, officially saying no to you. It's just that the nerdy dude in 1993, doesn't know the cute goth girl across town has zero interest in him.
Which I realize can be annoying as hell, but another thing to realize is a lot of women aren't actually on there to get dates, even from 9/10 dudes with penthouse apartments and ripped abs. They'll enjoy getting the match from that dude, but they won't give him much more attention than they'll give a normie.
I probably rambled a bit off-topic, but I really think Grey Tribe/nerdy/etc. guys end up in spirals of their own making, while a lot of normie dudes complain once or twice to their circle of friends, and that's the end of it.