Foster Care can be expensive. Without knowing what he paid each month, you can't tell if they actually made any money on it. I doubt it. I just don't think Family Services are competent enough to take advantage of it, even if he did pay alot. I spent 13 years in foster care, and have kept foster kids in my home as well. I have nothing good to say about Family Services. Incompetence should be their middle name.
My wife and I spent about 10 years keeping kids for the Illinois Child and Family Services, I doubt that they are any better than any other state.