Say that to Bayern Munich, they're always become a champion in Bundesliga for a decade which mean in there there's no balanced rival too, but they're always become one of favorite in Champions League. Remember we're talking about no rival and Champions League, not only the current season since Bayern Munich now has a new rival i.e. Bayer Leverkusen.
PSG is just an all star club without any strategy, that's why they always lose against all star club that play with a strategy.
Differences in quality and perspective of club management and applicable rules so as to give birth to a different vision. If I am not mistaken, PSG has just been built more coordinated after they have a new owner and he starts targeting the Champions League as the biggest achievement. In contrast to Bayern Munich and even there they have to make the rules at least German players must be more than outside players. Bayern Munich has become one of the best clubs when playing in the Champions League while the PSG level hasn't to that yet.
So that the project being worked on by Luis Enrique will be far more difficult where they have to build the squad to be stronger and take time so that PSG is able to compete in the Championm League. If Luis Enrique is able to build the club level to be stronger then I am sure they will achieve success as did Pep Guardiola in Manchester City.