He wanted to start his career, it wasn't happening at Manchester United. The fact is he was right in his move to Juventus, and came back here the most expensive player in the world at the time. There's no debate he was right to do what he did (maybe not to United fans, but to anyone else at least), but besides that exit which is all articles quoted by SAF who I'm pretty sure was not unbiased in his comments, where else has Pogba ever been a trouble maker? It's just not the type of person he is, he wouldn't have survived at Juventus or with Deschamps otherwise.