> why would these presumably superficial men bother sleeping with women "way below their league" when they could be sleeping with women in, or at least near, their "league" all the time?

The 10% of men having most women matches does not mean all of those men in the 10% have it equally easy. Hence it is easier for an average 10%er to pick without putting work instead of fishing for slightly better women... Pareto?

> Is the novelty of a constant huge supply of new partners really that important vs. having a slightly smaller rotation of people in "your league"?

Yes, at least for many men. I recall having read a study or article at some point that claimed that sexual attractiveness is higher the first handful of encounters with a given partner.

> This is the part of this whole theory that I don't really get -- why would these presumably superficial men bother sleeping with women "way below their league" when they could be sleeping with women in, or at least near, their "league" all the time? Is the novelty of a constant huge supply of new partners really that important vs. having a slightly smaller rotation of people in "your league"?

Not all top 20% are equal. For the top 10% men, sometimes the woman doesn't matter at all. There is no need to even try to maintain a huge rotation.

Sometimes they're just busy with work and don't maintain rotations. Other times they were bored and the first willing girl on tinder is ok for the night.

Sure, but what does it mean for someone to be "way below your league"? I take it to mean they're unattractive to you. Unless I'm misinterpreting that I just don't see the appeal of sleeping with someone who you're not attracted to.

I can only speak to my own experience, but as a 20-something male (now in my early 30s) living in SF, there were a lot of societal norms pushing men to have more sexual encounters. It's somewhat of a badge of pride to achieve a "+1" which is code for sleeping with someone new. Forces like this can lead to men working harder to have sex with more people for its own sake. On the flip side, women have many opposing forces to contend with like "slut shaming," which don't affect men as much.

Additionally, being above or below someone's "league" is a bit of an oversimplification, because there are multiple axes to attraction. It's quite possible to be physically yet not mentally attracted to someone, and thus authentically enjoy sexual encounters with people who you'd prefer not to date seriously, let alone marrying.

If you accept both of these situations, it's not difficult to imagine a world in which many women are having sex with men where there's mutual sexual attraction but no possibility for a relationship, because the man is only interested in sex. Of course this happens the other way too, although I'd guess much less often.

An ex of mine (who I'd remained friendly with) once showed me her Tinder messages and it was full of attractive, confident, successful men who clearly were only interested in sex with her, and who didn't mind being almost offensively direct, presumably because they all had lots of other options for sex.