Fans have nothing to do with this. They are basically customers, some with mental problems themselves, pay top money to jerks to be entertained. If these people aren't productive then they'll end up jobless.
My point isn't really about Sancho as a person. I wish him a quick recovery and tbh players contracts are written in a way that there's not much we can do but to keep paying him silly money and wait. My argument is towards the club. You see, there had always been players who were mentally weak. Taibi is a classic example. The guy was the living embodiment of Spurs. He was an absolute phenomenon at lower team levels but would bottle it at top levels. Prior to coming to us he bottled it at AC Milan which is why I never wanted him at United. You might think that weak character = poor talent but its not always the case. Some of these players were actually top quality players themselves. Roberto Baggio for example made Cantona look like Philip Neville and yet his weak character made him unsuitable at top level clubs. The guy was unstoppable at small club level were the pressure was low and everyone adored him like he was Christ on earth but once stress kicked in so did his paranoia which often pushed him to self destruct. In fact once the guy retired he left football for good and is now living as a farmer.
Well run clubs are supposed to scout beyond talent. They analyse the player's character and attitude to see if the guy in question can actual handle the stress at top level football. The same happens in house. Clubs tend to keep close tabs at their young talent. For example Giggs once said that whenever he organized a party behind the club's back, the first person who would show up at that party would be an angry Sir Alex Ferguson. Meanwhile rotten apples would be quickly shown the door with little funfare (ex Keith Gillespie or Bojan Djordic). United had stopped doing that from a long long time. We sign players on silly money/salary which is crazy enough in normal circumstances but becomes absolutely moronic when the players concerned lack the mental attributes (and sometimes even the talent) to succeed. This mismanagement is often felt at youth level as well. We let kids do pretty much what they want which is why we failed to benefit from the best 3 players coming out of the youth academy in the past decade or so (Ravel, Mason and Pogba)