I think it’s OK to be selfish, so long as that means prioritizing self-interest over that of others, rather than being greedy at others’ expense. And transitioning does not cost anybody else anything: you don’t owe it to anyone to be anything other than yourself.
After all, nobody is going to look out for your well-being as diligently as you yourself.
Hehe. I’d figured out that not every guy wanted to be a girl pretty early – that’s probably one of the reasons I was repressing so hard. But when I found out that actual trans people didn’t always know, and you could just… be trans if you wanted, that broke my brain :3