I think the issue at PSG is that the entire club believes its own hype - they've self-anointed as a giant/super club and have promoted themselves as such whilst having done absolutely nothing on the pitch to corroborate that. There is no humility or feeling of chip on the shoulder; they don't act like an aggrieved club looking to prove a point - they think, and more importantly, act like they are a Real Madrid or Barcelona at the height of their powers rather than a club who've not even gotten to the semi-finals of the CL despite spending over a billion pounds since the new owners came in.
I thought Rio's tour around the club and piece for BT Sport was revealing in that it showed a unit basking in being PSG and having the time of their lives in the city or with the fashion lines, or any other distraction that means squat on the pitch.
In terms of tangible substance, PSG still have no footballing identity and are more defined by these embarrassing defeats to clubs who are what they aspire to be. The only label PSG are earning is that of perennial failures in competition against sides who can fight back.
Stranger still, it is a squad dotted with World Cup winners and runners-up (Buffon, Draxler, Mbappe, Di Maria [runner up]), Champions League winners (Dani Alves, Di Maria, Neymar), players who should know what it is and what it takes to get to the very top - players who were star components of the sides who won the aforementioned trophies, and yet, we see those same players lulling into the hype machine they've joined and being complicit in keeping the side in a lower tier than they should be at for all the money spent. Dani Alves, the multiple Champions League winning veteran, is the player doing keepy uppies and not at all focused on the task at hand - imagine him doing that in the ultra serious environment of those Barcelona CL winning sides midway through a tie that's not close to being over!
Until PSG as a club feel genuine hurt and humiliation to the point it focuses the collective, there's no reason not to think these knockouts that make a mockery of the expenditure won't keep happening. It's not a managerial issue, not even a personnel issue it's taking in an energy and core outlook that you have no right to have until you're a multiple CL winner.
It feels to me like PSG could constantly switch managers in and out, but the mixed messages of what the club stand for is always going to cause a problem - you cannot bathe your squad in external adornments or pander to them in a way that makes you look simply grateful to have them there - that's a cornerstone for unprofessionalism and minds that are not as focused as those of their opponents who are not privy to such pampered conditions nor told they are amazing at every turn simply for signing on the dotted line. If PSG want to be a giant, they should look at how the giants do it and mirror that instead of trying to be both friend and disciplinarian at the same time, stop rewarding failure and take on every CL KO game as if their lives depend on it.
Further to that pandering to players, it's not a club where top players have to worry about consequence or being ousted from the first xi due to competition for their place, this needs to change and you'd see the level of professionalism increase immediately.
It's not a surprise Cavani is a (the) fan favourite as he is the embodiment of the qualities you need in a team who are chasing the most elusive club trophy in Europe. His attitude across a few more in that team and you'd have a whole different problem facing off against PSG.