Indeed, I heard that Messi wanted to go to Barcelona because of the family's request. But another factor is the pay cut from PSG and fans who are not friendly with Messi's current state. I heard Messi's salary will be cut by 25%, this is to remain eligible in FFP. But this is only a rumor. I myself find it strange if Messi comes back. They have started to come out of Messi's shadow with young players who continue to develop. Signing Messi may be an instant solution to the frontline problems but it has a bad impact for the long term.
I actually see it from a different side, Messi presence in the Barcelona squad will further improve the quality of Barcelona's game. Messi will take on a new role this time around, he will be shifted to the center to serve the attackers with his beautiful cross. He can also set the rhythm of the game well, the 4-3-3 formation can still be used with the current attacking scheme, Messi will fill in as an attacking midfielder.
Young players can learn directly from Messi, his presence in the squad can help their development. Dembele is one of the players who experienced rapid development when playing with Messi. Messi presence will not cause problems in Barcelona game, he is not the type of player who is hungry for individual titles. This time, his status as a teacher for other young players, his existence will really help Barcelona in the title race in the following season.
Why would Messi go to Barcelona? Except for the fact that the coach is Xavi right now, I don't see any other reason for him to go to Barcelona. At this age, he can easily go to MLS or the Saudi League to basically chill and get a big fat paycheck. Why would he need to go to Barcelona to prove something that he has already done?
I understand that young players will be able to learn from Messi. But there was a time when he really wanted to stay in Barcelona but the Barcelona authority basically did not let him stay. I would say he should go for the 400 million.