Ronaldo in the last era of his career thought about going back to Manchester United where he feels is his home, but it actually didn't work for him so he decided to change direction. This days, players decide to end their career in a well paying club. They desire making a lot of money in the last season of their career than going for achievement. Lionel Messi return to Barca would have been an exciting thing, but I'm trying to  fathome what will be the brain behind his return. But I'm sure it will not be to win more trophy or end more personal honour, it will only be  as a way of paying last honour to FCB, and such will not amount to paying him much like u said.