I have a cousin who lived high on the hog for quite a few years taking in foster kids. Yes, he got paid for each one so took as many as he could get.
He actually wound up adopting 3, 2 brothers and a sister. Never could figure out why he did it since the money stopped after that.
Maybe because he began to genuinely love them and wasn't an opportunist look for just money? The couple were obviously just in it for money.