I dont think that has anything to do with it. Idiots find it easier to abuse him, because he reacts so badly to these abuses. They know they can easily throw him off his game by abusing him.
Also every abuse directed towards him is not racially motivated. If he played for Milan or Gobbi, he would be our most hated player. Piss poor attitude, dives like a little bitch, ego of C.Ronaldo with out having achieved 10% of what Ronaldo has achieved. There are so many reasons to hate this guy, if you are on the opposing team.
Lastly, Balotelli just seems to me like one of those guys who will keep on crying about racism or the rest of his life, with out actually doing anything about it. When oppurtunity knocks on his door, instead of opening it, he will start crying about racism. He has a victim mentality and an attitude of the world being against him. He is not really gonna achieve much in life unless he changes that.