It's a big dream for people that think it's possible for PSG to win UCL, because they don't have the quality. When Messi, Neymar and Mbappe was in PSG was the best time for them to win it, but they couldn't. PSG is struggling to survive from the group stage in UCL this season, and scoring goals is like a big problem to them. If they qualify from the group stage, they might not make it out from the round of 16.
PSG mistake at that time was just too often giving big salary offers to certain players and relying too much on them. I mean when Messi, Neymar and Mbappe were still with PSG, the three players seemed to only expect big salaries without having to work as hard as possible and the reason was only about their old age and Neymar had a serious injury. On the one hand, the team coach is also an important factor for the team to be able to get stable performance. And now for me PSG is much better than relying on star players and now PSG is more focused on improving team performance with cooperation between reliable players.