At one time PSG spent the most money in terms of signing players but they still have zero achievements in the Champions League. No matter how much money a club spends, if the players don't have a good relationship then the club spending that much money is a total waste of investment. Mbappe, Neymar, Messi are very important stars of these three clubs, but Mbappe and Neymar's relationship is bad. Mbappe and Messi's relationship is bad, that is, if there is no good relationship between the three main stars, how can the team's performance be good. PSG could not do well in Champions League due to lack of good relationship between players, lack of good quality manager in the club, lack of good quality midfielder in the team.
Just spending money and having success is not good deal which is clearly showing in few leagues with top teams like PSG and Chelsea both spending huge amounts but sadly still looking for their first win things never been working on merit with they need some patience and coordination between players as well because without this we can expect positive results after departure of big players suddenly PSG is having goals drought which is surely big concern in last two games they have just one goal which scored by Mbappé on penalty.
But we can expect good changes because new coach is good and need time for adjusting players and working on his strategy which will surely help them for having better result in coming weeks now after departure of Neymar and Messi Mbappe is alone with Dembele so can he lead from the front, and they can lead from the front it's a big question which is looking for the answers.
To me both clubs spent these money on wrong players that is the different, that is why Psg has not achieve Champions league, last season they brought in wrong set of players with huge sum of money, yet they did not achieve any good result. same with chelsea, they bought so many players last season , young stars into the club but are still performing badly week by week, no change, in spite of the coaches they have changed to better the team, look the way Real Madrid and Manchester city sign players, they don't just sign to get media attention, they sign who fit into their playing pattern. that's why they are super in their respective leagues.
Psg and Chelsea should not be signing so much players,its difficult to manage them, puting alot of pressure on the coach.