I think what needs to be clarified is that players who are active in this business perceive football different than fans do.
The choice of some fan, which club he supports or wether he changes a club has no real outcome on his life, football is just passionate entertainment.
But for players, this is their job, football is a business, at the moment where they enter the big stage, football inherits their whole life. Decisions like switching a club, are affecting their whole career and their career is what they define themselves on. Everyone tries to achieve as much as possible because this means a better life. If a player has the feeling that he is getting stuck at some point, then he might come to the conclusion that leaving might be the right step.
He might have been just as much of a barca fan like all of you here, but he has to prioritize his own life over the club. We as fans are in no position to judge players, those are just humans who try to perceive a career.
The ideals that fans apply on players, are always biased in favour of the club. They demand players to take the club over their own life, but 99% of them, wouldnt do so in similar situations.