I suppose it must be an accumulation of the years of hatred, discrimination and rejection they encounter on a daily basis. I mean look at Tyler Robinson, it was obviously this which drove him to kill Kirk, he knew Kirk disliked him for being gay and he couldn't handle it. I suppose if you get rejected, spat on, disliked, beaten up and insulted on a daily basis it ends up eating you up inside and festering until you decide you will take no more and retaliate. Another interesting question is why the gay community is so prominent in the history of treason. Gay Burgess, Anthony Blunt, Alfred Redl, John Vassall, Donald Mclean, Chelsea Manning. It's a long list.