Most times it is not all about the greatness of the players that wins the match, especially when it is Champoins League.
So, while talking about the greatness of the players, let's consider the greatness of the team in terms of experience in Champions league.
Real Madrid as players have better experience of Champions league. Even as a team, they have better experience of Champions league more than always exiting PSG. So, I expect RM to succeed this stage no matter how formidable PSG may appear.
Yes, it's true as you say because there are many examples like last year when Chelsea won the Champions League and not many people even made predictions that Chelsea would win at that time, but in terms of matches the experience of a club and a good player is a combination which is very much needed for a club because therein lies a power that cannot be read by the opponent.