Why do men think it's okay to bed a women, have a child and disappear?

When by law, they must at least pay for child support. They try to evade their responsibilities as men, and overall human beings. I don't really understand how these kinds of people can call themselves men to begin with. You have a child, you should take care of that child. Why don't some of these men think that what they are doing is wrong? I am curious, do they not have a conscience?