Has he ever revealed why he decided to leave barca?
No, he has never revealed it, not even to his own family. These are my conclusions based on inside information coming from his own family.
Victor Valdes 4 main reasons for leaving Barcelona in order of importance
1. Ginés Carvajal talking him into doing it.
2. Greed (60 million is more than the 36 or 34 he was going to get from Barcelona)
3. Resentment towards his own family (Father and Brother) for mis managing his wealth ultimately indebting him (this is why he sold his mansion in Gava to a Ukranian in 2014)
4. The guy is a head case, and most probably we have not seen the last of his antics (He made a fool of himself at United)
Nr 4 maybe should go nr 1, Victor Valdes really is a head case, it runs in his family and it is probably inherited, he comes from a family with generations of functional "crazies", in fact his brother works as a psychologist and has a private clinic financed by Victor. I am convinced he really lost the plot when Iniesta got a salary raise ahead of him even though he was a senior player with more seasons and matches played than Iniesta, this became a ghost he could not get rid of, combined with all the other shit going on in his life, breaking up with his family after they screwed his savings and losing his personal trainer of 7 years (Juan Carlos Unzue). It made it inevitable he would blame the club and Zubi even though all they did was standard practice.