When PSG still had the deadly trio of Messi, Neymar and Mbappe on their front lines, it was difficult for PSG to win the UCL trophy, especially now that they only rely on Mbappe who is supported by another partner beside him. The UCL trophy is still PSG dream, they always try to win the trophy but always fail. Mbappe, who is a mainstay on the front line, has been continuously rumored to be leaving for another club.
You could argue that three world-class forwards are not a guarantee that your team will win trophies, especially if your midfield and backline are mediocre. I remember hearing pundits and analysts claim that PSG didn't have any tactics and just relied on their three forwards, which made them unable to compete at the highest level. A bit similar to Madrid, with arguably different levels of players. Maybe they need to change their approach since it clearly shows that buying expensive players alone doesn't solve anything.
I'm not sure their fans would support a coach like Klopp or someone similar who needs time to rebuild and instill a tactical approach if it means benching some of their superstars though. A club should be bigger than their players, which is not the case with this Mbappe drama. CMIIW.