I think Lionel Messi was not used well by the PSG team. Because with Lionel Messi you can achieve something unique. I think the PSG coach doesn't know how to use Lionel Messi. If Lionel Messi got a coach like Pep Guardiola, he would have created history by now.
I think the three main factors that are very important are comfort, the coach and the support of the supporters. It looks like Messi went to PSG because the salary is quite high for an age measure like him. In addition, in Paris Messi does not seem to have gained comfort in life. Then PSG fans also insulted him a lot because of the bad game. I think this accumulation made Messi have to leave. He needs a place where they are rewarded for the effort they have put in. A short year of time, but Messi is gone it proves PSG is not the right home for him to retire.