Well Messi is probobly full of playing football and just wants to have fun a little and earn a lot more money in the last years of his football career. After he won the world cup he dosent have to win anything so there isnt anymore motivation for him to play at the top quality level as before.
Today, football players can continue to play football until their very old age. One of the best examples of this is Ibrahimovic. Even if Messi does not play football until the age of 42, he can play professionally for a few more years. For this reason, it is a very correct decision to choose to spend his last years in an easier league. I thought he made the right decision when he moved from the Spanish league to the French league. Now he will most likely go from the French league to the American league. I think we can say that he made the right decision again.
In fact, players can force themselves to continue playing even though they are no longer young, even old for a professional soccer athlete. But the question is whether he will be able to continue to compete with other young players and continue to be the first choice within the club. I'm sure players who have decided to retire also still want to continue playing, but when they force themselves they also consider the things that will happen to them. Especially now if an athlete is not good at maintaining his health and also his physique then they will no longer be able to run. There are many players who, even at a young age, feel physically lacking for a player.