I do not agree that all the clubs in the Ligue 1 has actually given up, they do want to win the league title just like PSG and remember few seasons ago we had Lille winning the Ligue despite every attempt by PSG that season to win so I do not want to believe they are not working towards winning, last season we saw that Marseille finished second although with a poor attempt but they look forward to winning the title some day only that they are yet to have the form that will position them right enough.
It's the same Lille that won the Ligue 1 some seasons back like you said that could not finish in a champions league competition spot but were rather content ending in the 5th spot just last season so you can agree that it seems that the other clubs are content in their various spots rather than contend with PSG. You may disagree that these other teams have given up but from their actions, you can see that they are not putting much efforts.
The funny thing is that PSG have shown that they can be beaten so why do the other teams feel it's a difficult task? Is it that they haven't studied the pattern of play that PSG uses or what?