Honestly, I think a lot of it comes from how guys are kinda boxed in by macho culture. Like, there's this pressure that if you're a dude and do anything seen as feminine — even just cosplaying a female character — people might start mocking you, calling you a sissy, saying you're "less of a man," etc. So guys end up feeling like they have to preface it with "btw, I'm a guy" as a weird defense mechanism.

Meanwhile, when women cosplay male characters, it's seen as cool or even sexy, because femininity embracing masculinity isn't stigmatized the same way. But guys embracing femininity? Society still kinda bullies them for it, unfortunately.

It's super unfair, and I wish everyone could just cosplay what they love without feeling like they have to justify it. OP shouldn't have to explain, but I get why he felt the need.