The bookmakers can give the winning odd to whichever club that they want but that isn't a guarantee that the match will finally end up as predicted by the bookmakers. I have the same feelings that Inter will be the winner of tonight's match because they look more desperate than PSG, if we want to judge from their previous performance.
Bookmakers make millions of calculations. They take into account every possibility. They take into account the money betted on the teams. They look at the risk and reward mechanism. They set and change the odds to be the most profitable for them. Bookmakers don't make emotional predictions, they don't give emotional odds. They only look at the math and the profit.
Today the PSG odds are lower because they are the favorites in the match. That doesn't mean that PSG will definitely win the cup, if that were the case, the matches wouldn't have been played at all. There is no such thing as a guaranteed win in betting. Sometimes the bookmaker wins, sometimes the bettor wins. But when you make a total, the bookmaker always wins in the end.