Asked a big salary that Barca weren’t willing to give. Also at that time looked like his development stagnated a bit, he was very highly rated since he was very young but in the final years other players went past him. He wanted a clear project and Barca couldn’t promise anything. Also got Raiola as an agent. Many reasons. I think it was probably wise of him to change the scenery and get a fresh start. Here he was always known for his name and hair, got a million followers at 15 playing youth football etc.