I see this all of the time on here and it is disconcerting. I think most of the people who get in to these verbals wars do so because they are not 100% sure about what they believe in. They are trying to validate themselves somehow. I don't think their intention is to help people, I mean you...
He is 17, what do you expect? Just stop paying for him to eat, I am sure he manages when you aren't there. Does he spend time studying instead of working to appease you? Or is he blowing his money on crap? There is a big difference.