Because there are some problems that will definitely happen if he chooses a club, especially since he is already considered a legend in several clubs, so he will definitely have a little trouble with that.
Being at PSG is indeed very good but the problem is that it will also be very difficult, especially now that there is clearly a financial fairplay that regulates it, although things like this don't seem to apply to PSG but still it is a little difficult because there are already full for the front lines.
Apparently, Bayern Munich is really not interested in Ronaldo's services, because representatives of the club consistently deny the possibility of a transfer of a football player. Now the CEO is Oliver Kahn. he said that Ronaldo is one of the greatest footballers, but this transfer does not correspond to the philosophy of the club. It's a pity, because in my opinion, after the probable departure of Lewandowski, Ronaldo would be a great replacement for at least a couple of seasons. The option with Paris Saint-Germain is unlikely due to the financial fair play and because Neymar stayed at the club. I am almost sure that Ronaldo will not agree to a significant salary reduction for a move to PSG when Messi and Mbappe have such high salaries.