Maybe I think otherwise and these odds are quite feasible for PSG because after all Monaco is one of the strong teams in Ligue 1 even though they are often less consistent. On the other hand, the meeting you mentioned is also enough to influence PSG's odds of winning to become more feasible and with this it is certain that PSG will be favored to win at home.
I don't see Monaco being a serious threat to PSG and if PSG can lead by more than 2 goals, of course it will be over for Monaco and they will definitely have difficulty equalizing. So I think PSG will win by any score and this will be what they deserve to maintain their top position from week to week.
If you look at strength, PSG is indeed much stronger, but this season PSG is often inconsistent and so is Monaco, this is the same team that is inconsistent in my opinion, so anything can happen.
While the smaller odds for PSG are indeed feasible because the winning percentage is greater for them because it all looks at the team's strength.
For the whole of this season, even though PSG is inconsistent, I don't see any strong competition from other teams to stop PSG from winning Ligue 1 because other teams are also inconsistent, so no one can take advantage of PSG's underperformance to leave them on the standings.
I do not think that PSG is as inconsistent in the league as people think they are. They didn't had a great start and that part is true but then they ended up being so much better, and won plenty of enough games to be at the very top once again. When a team is at the very top, it is possible that they could end up losing games or getting a draw, nobody at the top just goes unbeaten forever, but it also means that they probably have a higher chance to win their games than anyone else as well.
This is why it's smart to bet on their win, they will probably beat Monaco and keep on being the leader of the league, is there a chance for them to fail? Of course there is, but I can't just bet on the off chance that PSG may end up losing points, it's much better to bet on them to win every game, even when rarely you are wrong, it still means that the wins would cover the difference and you should be profiting from them enough to cover the losses here and there.