Maybe I am wrong and in the minority with this but I need to speak up for Dean. I don't think it was cockiness or selfishness on his part, he would only have risked the money in a game if it was necessary, they never actually specify how much money was involved but I think perhaps something came up and the money he had was not going to last as long as needed. He definitely would have turned to what he knew gambling and stealing. He just would not have risked Sammy being hungry. John leaving him in jail does not seem in character to me because of his need to have them safe, Dean was left unprotected and I just can't see John taking that risk. Good story though.