Yeah I think when he started this site, it wanted to be legit. But at some point he decided that stealing money is way easier than actually earning it. Everyone has a price, a few hundreds of btcs (when they became worth 1000+$) was bit365's price for him to go "breaking bad". Or maybe his wife left him or his dog died, who knows what made him tip over... As long as he stays anonymous, he is not risking much by scamming people over and over.
Unless you've planned it long in advance it's not particularly easy to remain completely anonymous as there are always records (both your login IP and domain registration) and other data you may have unknowingly provided that allows people to work out who you are. In this case, I'm not too sure whether he's gone scam or he's delaying the payouts for some other nefarious reason as I don't believe his excuse of losing his cold storage wallets.
Light has nailed it on the head.