Actually, some pro-aborts just hate humanity and think it needs culling, some are in it for the money, and the rest like the fact that it's easy and convenient and don't really want to think about it.
True. It was really scary to see how many people agreed with the Unibomber's views.
They justify their views by claiming we're on the verge of a Malthusian overpopulation catastrophe. Of course, even if true that wouldn't justify murder, but it's just another liberal myth.