Is there any reason other than validation for men to pursue sex with other people?

As a man, I assumed for the longest time that men pursued sex with women for gratification/pleasure. But the more I browse this sub (and other subs) the more obvious it is that pleasure is not the primary motivation. After all, pleasure can be more reliably self-stimulated without involving anyone else. Pleasure is actually less likely when another person is involved due to the extra work of coordinating and staying in sync with them, with more things that can lead to dis-satisfaction. So if pleasure is ruled out as the key driver, then the only thing left is insecurity and the need for validation.