Money isn't the issue here to be fair, they have teams worth of hundreds of millions of euros, which is more than a lot of teams who wins the Europa or conference, so they could have a team win.

PSG is also good enough to win the UCL, a huge club with an owner that has deep pockets, so they built many good teams over the years, and spent a lot of money on the club as well. What they are lacking is experience in tournament schedule, they are just not experienced in it which shows itself during the European competitions. Too many teams go up and down, and not a lot of them joins the same competition every year, aside from PSG that goes to UCL, and I think they need to learn to be better at tournaments, which will help them on the long term.