I get your point, but PSG is among the elite teams right now. They have the players and they have what it takes to win the Champions League. They've just been run very poorly. It has nothing to do with the league they play in. A good team is a good team anywhere, the league doesn't matter. If they are very well managed they should be able to win the Champions League.
Manchester City is almost the same thing with PSG, the only difference is Man City won the Champions League last season which is about 6 seasons after signing Pep Guardiola.
My point is, that it takes time.
It's worse for PSG because they don't know how to manage the club. They don't know how to sign players. The fans decide a lot of the players they sign. When they had Messi, Neymar, and Mbappe, they had a very average midfield. Good management should know that the team needs to be balanced.
A well-managed team would have let Mbappe go last season instead of giving him such a huge contract. They keep building their team around one man and it has never worked.
They need to have a balanced team where the team depends on the team to succeed. One man can't carry a team except you're Lionel Messi. Even Messi needs support, to be honest.
Oh I don't think you fully understood the point I was trying to make. I do agree with the most part of what you have written, but do you remember that Ronaldo said the competition with Messi is what made both perform at this insane level for such a long time? Great teams and great players are pushing each other, they make you shift your own performance boundaries. PSG doesn't have opponents that put them under pressure, but then suddenly they need to play the best game of their life. Manchester City, in contrast, is playing against Liverpool, Arsenal, Tottenham, Manchester United etc. on almost a weekly basis. In my opinion this makes a huge difference because players have to be sharp nonstop. There is no negligence possible at any point in time during the season. PSG players can lean back 70% of the time during a season. Once they have a 6 points advantage, the season is essentially over.