Because they have money, it's not fair for A class player to fight with C class player. If other teams have the same financial status, every teams will have a same chance to become a champion. Take a look with Serie A, there's no big gap from top 1 to top 3 teams, that's why either of them are become champion.
While PSG is like a combination of 3 teams in Ligue 1 lol.
That's the reality in Ligue 1. so don't be surprised if the champion every season is PSG, even though there are clubs like Lille and Monaco who have competed with PSG. but still, PSG is a very rich team and there is quite a distance from other clubs. that's what makes the competition in Ligue 1 less interesting to me.
This season may not be much different. there are no strong competitors for PSG in Ligue 1, but hopefully there are and it will definitely make it more interesting for a competition. maybe it will also help PSG to develop with better competition. because competition in the league also helps them develop when they later face other strong clubs in the Champions League.