Why do people with homophobic/transphobic etc. parents out themselves to them while they are still financially dependent on them?

I got a trans buddy who is about to lose everything and is highly depressed because his parents are disowning him and maybe even kicking him out. You can probably guess why because of the title. This is something I've heard SO often on social media and even in pretty well known movies and shows and I just don't get it. I obviously understand that you want support from your parenty and I do get that part, however if you already know your parents/friends stances on this stuff, then why are people still doing it? My friend has told me 100+ times how racist/homophobic/transphobic his parents are and he still came out to them? He has no job, no other place to stay, 100€ in his pockets at best and is basically fucked. I knew this was gonna happen. I told him this was gonna happen, so why? He has support from his friends so it's not like he had noone to talk to.

TLDR; Trans guy came out to parents who are openly SUPER transphobic and got the obvious reaction and is about to lose everything.