People always forecast anything base on the history, so they think Real Madrid is the strongest team in UCL and Sevilla is the strongest team in UEL. The luck that those teams have in the past seasons make they think Real Madrid and Sevilla will have a same luck in the future.
It's correct a new strong team might challenge them, but not every time.
That's what I think as well, but it's bad that people draw these weak conclusions. Experience plays a role and that is why teams who have won a title before can indeed have some kind of resistance in difficult situations during a game that other, unexperienced teams might not have. But all of that is worth nothing when you get destroyed by a team that is simply better like we have seen in the Champions League. Sevilla had a remarkable Europa League season, but they won't repeat it. Nominating them as the favorite if they get eliminated from the Champions League seems irrational to me.
And if we think about psychology, we can also say that Real Madrid is superior going into the Champions League because they have a very good record in the competition. So that puts them at a psychological advantage against other teams. But we all know that psychology is not everything. If you cannot actually perform in the field, psychology is not going to matter too much. First of all, you have to believe that you can win. And after that, you have to put in the best effort. Anyway, it is not impossible for a young club to give teams like Real Madrid a goat competition. But I also agree that it is not going to happen every time.