I think there's a particular brand of person I've seen a few times in real life and in media who gives off strong incel energy despite regularly having sex, and I think many of these people are the same as you describe. I think the toxicity that gives them the incel vibes are a product of "I have been conditioned to chase after sex and to measure my worth in how easily I can acquire sex, and now that I have achieved that, I feel hollow because it doesn't give me fulfillment"

I spoke to a guy friend about this and he said that his own experience of losing his virginity in his mid 20s gave him a sense of discomfort that he later recognised as a sort of gender dysphoria (as a cis man), because suddenly he was "winning" at being a man (according to how society tends to frame it), but he was less happy than before.