I think the numbers end up being about 5-10% of all mammals show homosexual tendancies/behaviour. As far as the other parts of the non-hetero community it's a bit tough to show that in animals you can communicate with.

Lots of things that don't seem to benefit survival show up in the evolutionary tree of life, so who knows really.

Nobody knows why homosexuality is part of all mammalian life, even some birds too I think.

It's also pretty juvenile to think of it as "beating" it.