I guess it is the illusion of converting someone, doing something other have failed to do, seducing a guy is not enough, it has to be a straight guy.
As a straight who a few times got hit on by gays i find it kind of funny, but than again there are so many of us who think the same about lesbians, it is the aiming for the stars to convince oneself of being a true space invader.
If you ask me you will get no for an answer, and if you try to get it a different way it will not change, you can't change people, either they are into it or they are not, all you can do to get them to do something they are not in to, is trick them or take advantage of a weak moment.