It is an easy league without competition for PSG. This league doesn't look attracting for investors much as well so it looks like PSG will continue to dominate it for long years. But if we see another team having a rich owner in the future then maybe the champion would start changing more often.
For now it isn't possible unless PSG give it away.
When it comes to Mbappe the reason why he stayed this long is money. Nobody knows the exact conditions of his current contract. It is that big.
But from now on I think he will think of making a change more seriously. Because PSG can't win a Champions League title. For a star like him winning that title is really important, to have a bigger career. Real Madrid is the right place for that in my opinion.
Among the top 5 European leagues that exist today, of course, Ligue 1 is the least competitive league, so it is so easy for PSG to dominate the league without competition from other teams at this time, but unfortunately when PSG looks very strong in Ligue 1 at this time but unfortunately they are actually unable to do the same when in the Champions League competition, and it can be seen from their failure so far in Despite Messi, Mbappe and Neymar in their squad, reportedly many big investors are difficult to invest in other teams in Ligue 1 at the moment, I don't know what happened but it seems that every investor who wants to enter is as complicated to take a team as it was when Marseille wanted to be bought by Arab investors but faillure.
So far I think PSG not only control French football, but we can see how PSG seems to get into French politics and it shows when Macrom (French president) interferes with the issue of Mbappe transfer so far, what you say is true, because indeed we would never see competitive competition in the French league if there were no big investors who wanted to take over other teams in France later.