Every kid these days goes through the AAU process. This is not Marvin's issue.
Marvin is going through a maturation process in the spotlight of NBA fans. How he responds or reacts to his situation is a factor of many things. All accounts of people that have had interactions with him say that he is respectful, hard working and a good kid. He's very close with his family and by all accounts, his upbringing has got him pretty darn far.
He enters this environment where the fans say he doesn't work hard, is a malcontent, he's a bust, trade him for a bag of chips, etc. Common sense tells you that Marvin is going to lean more towards the people who got him here and not the ones trying to tear him down.
With the negativity thrown around, at some point a person is going to go into self preservation mode. For all the folks saying he is putting the blame on other people and not taking responsibility for his actions, are fans taking responsibility for theirs? He literally said in that interview that he needs to take control of his situation to achieve his goals.
Marvin is supposed to not listen to the negativity from fans, media and social media. He's not supposed to listen to his father or uncle or any family. But he's supposed to care what people say on social media about what he does. He should praise the fans and city and denounce his family. He's supposed to take the advice of the media, fans, etc who all claim to know who he is, what he's thinking and how he goes about his day.
It really is time for him to move on, because there is absolutely nothing he would be able to do to make this city happy. Personally, I think he realized that at seasons end and really couldn't care less about what the fans say anymore.