i mean, its not really a matter of what you believe, but what the truth it. multiple g4p actors have come out and said they do not like gay sex and many drugged themselves to get through scenes. i highly encourage just like, a simple google search about it.
as for why, a lot of possible reasons. a lot of yall do not understand porn, and really think you show up and get paid to fuck and thats it, but there's a lot to it, like any other job. the 2 biggest factors i know of though for why people pick gay porn instead of straight, are the possible money made and the demand for you. straight porn is saturated with dudes trying to get into it because they think they get paid to fuck hot girls and thats that and a lot of studios turn you away because you cannot meet standards for work and/or just general demand. on top of the fact that unless you get really popular/a lot of work, youre not getting paid that much (ala johnny sins/jmac/etc type popular) whereas gay porn, there's a high demand for constant new men and the pay is good even for a "beginner"
as for their mental health, i have no comment on that other than, as a branch to what someone else already said. a lot of yall refuse to acknowledge anything that breaks away from this fantasy that hot straight guys wanna fuck gay guys and are secretly gay and waiting for hole instead of like... just like anyone else, they need money for whatever. i highly encourage a lot of you to look at porn directors like jasun mark, who talk about the industry