It happens in schools too, where the kids that are doing okay get little support, while the one or two psychos take the majority of time and attention. I understand it more in a school though, as for the most part, all the kids are innocent in the circumstances they find themselves in.
I have a friend who is a top heart surgeon here and half of his patients die. The reason is that they hand him the worst case scenarios that are already so far gone, there is not much that can be done, but if there is something, he will be the one who can likely do it. Perhaps his effort would be better spent on others.