I can't help but think that a lot of resentment from guys who aren't getting laid comes from society's notion that if you can't or don't get sex, it means you're a lesser human being and that makes it okay for others to hurt you. In that position, I could easily see a man resenting women as the gatekeepers of his full humanity, and that by not having sex with him, they're depriving him of it. It's very similar to some angry thoughts I had when I was younger, and in a worse timeline it's entirely possible I could've fully plunged into that same cesspit.
That isn't to justify any of the awful shit that incels say and do, of course - many reactionaries lay blame in the wrong place for very real problems they face - but I feel there has to be a connection there.
The value of virginity probably changes depending on the gender, but even in spaces where men are explicitly told its cool and good to "wait for marriage" it's still important to be seen as being able to get some (and judging by the frequency of youth pregnancies at those sorts of churches...) even if you outwardly are not having sex