Should I just sit back and watch the train wrecks over and over?

My brother in law is probably a sociopath. That's the medical term for it, I think the spiritual wording is, he just doesn't have a soul or conscience. I keep seeing him get into one relationship after another knowing he is just lying his a** off to these ladies. Usually it is too late to say anything to them, as they are usually married to him or pregnant by the time we meet them. He wrecks their credit, has kids w/ them he'll probably never support or see later on, and causes them nothing but heartache and trouble. He's also a drug and alcohol addict. The last time he brought home a woman (already preggo by the time we met her and engaged to him), about a month or two befor hand he told us he was going to find him a "sugar Mamma". She used to have perfect credit, now it's in the tank thanks to him. My hubby tried to sell them a car, and he said he'd never seen such bad credit. Should warn the women he brings home? I am afraid they won't listen, and will tell him.