It's quite strange with what you said when you say that PSG should focus on the current ligue 1 trophy instead of the champions league, try to pay attention to ligue 1, don't they win the ligue every season unless there is a team that is able to break their dominance in ligue 1 so far and that happens almost once every 10 seasons,  currently PSG has a star squad and has quality that is far from other teams in the ligue 1, but for some reason you doubt they can't win Ligue 1 trophy even without Mbappe?
During this time Mbappe has developed rapidly into a star at PSG and even when he was still playing in Monaco before Mbappe was not star player in Ligue 1, at that time without Mbappe in the squad, PSG was able to dominate Ligue 1, then why can't PSG do it now without Mbappe?

Mbappe has indeed had a great influence on PSG attacking line so far, but that does not mean that without Mbappe, PSG will lose its dominance in ligue 1 next season, currently what PSG expects is the Champions League trophy and without star players it is of course difficult for PSG to be able to compete in the Champions League next season, that's why currently PSG is more inclined to strengthen its squad every season just can for get the Champions League trophy for the first time in the club history.