> people like you will, all else being equal, surely get outbred by people who do care about their progeny. So why worry? The tendency to hold your point of view will wipe itself out...

That could be true (though, atheism is on the rise, despite religious people having more children than non-believers on avg). But it's also orthogonal to the question at hand. Existence or non-existence of proponents of a given POV at a given point it time doesn't say much about the validity of the POV itself.