You have done so many things for him it is a shame for someone to act like that. It is wonderful how hard you have tried to keep his head above the water even though he doesn't seem to have any concept of money and the value of hard work. As long as you are currently not being harmed by his need to be depressing I would suggest you do be the bad guy. A friendship does not work if it is one sided nor does it work well if someone is lazy. You have done your duty as a best friend to push him towards being an adult, but his parents attitudes have caused him to believe that he can go through life this way.
If you still feel it is necessary to try and push him to grow up you will have to confront him as a bad guy, but do it in the right way. You have stayed around, because you care. How many people have stuck around for this kid? It seems like you are the only one.
He probably got on the wrong path already before 5th grade, one way or another, causing him to lose hope in either just the education part or the job part as well. It might have been a difficult time for him, or he actually has a learning disorder. 5th grade is already way too late to get him on the right road with that, and now is no better. I doubt this guy will end up with a job, so all I can hope for is that you have a good welfare system in your country. You pushing him will most probably push him, if anywhere, further from you. It's sad, but most probably true. I can understand why you are worried, I bet he can as well, and the only thing needed now is for you to understand why bothering him with this isn't very likely to help. Let him take his own consequenses and keep him as a friend.
I mean, I have my moments where the future seems hopeless too. He has a pretty wealthy family and all of the resources needed to get far in life. He just needs some drive. I have to apply for scholarships and loans while his family can just write up a fat check.
Eh, my boyfriends family are well off, his brother can have anything he wants, but it still won't get him anything in reality. We all have to go through hardships, he just doesn't realise his parents wealth IS his hardship. Its their money, not his.