WHY CAN'T A DAD BE A DAD

I'VE always wonder why do some of father's in the world today have to have sex while their young with a young girl and get her pregnant and leave and not be part of that child's life when they have made the child also. Young women need to make wise decisions about who they sleep with especially when the guy only wants to sleep with u and doesn't want to be with u and treats the women very bad and that's why i never understand guys and why they decide to do that it makes the guy seem to be careless and mean irresponsible and unattractive. i know that it is hard for the girl to take care of their child too with. that's why i always wonder why do guys just get up and leave their kids and not take responsibility.