Actually... I can see it. Incels are of a very low quality type of man. I hate to say it but I was surrounded by them in my youth, before that was a thing and they were just nerds. They were extremely aggressively unhappy about not getting girls. It never occurred to them to work on their personality and stop whining.
Anyway I am kind of squinting back across the years and thinking of some of those guys and the late night drunken conversations in uni halls and I think I can see some looking at the kind of attention, camaraderie, automatic acceptance, membership of a crowd of misfits who are seen to be 'cool' aka the lgbtqs and going, that will be a way to end my loneliness.
The sex part if probably second to the loneliness, but they probably think there are going to be all these trans men there who are looking for women (who arent allowed to say no to trans women) and that these communities will be more open to sex with anyone so will increase the odds of getting some themselves. Being lonely leads to acute madness and I think more and more that this is where all these new trans indentities are coming from. When the fad passes, or the community fractures (as it already somewhat has) when the ones who are normal realise they keep getting complete sociopaths, nutters and just awful humans trying to join, the nutter crowd will have to go find another new fad.
Not totally sure that will happen. It's not like other nerdy outcast stuff like... rock music, larping, gaming, ultimate frisbee etc. The LGB and legit T people will still be there, wanting their community. I feel sorry for them that their part of the world has become a stupid fashion trend for social outcasts. Now THAT is homophobic and transphobic.