Yes, players moving to European teams from everywhere in the world, including South America, is why the European teams are stronger. Acknowledge that doesn't suddenly make the European teams not stronger.
Also, I'm not too knowledgeable on São Paulo's club world cup victories, but I'm pretty sure they won one over a team you didn't even mention. You're also calling the Champions League "EuroCup", so yeah, not a lot of reliability there.
Edit: and no, no team goes to a club world cup with the intent to lose, but it is undeniable fact that south american teams are usually far more hungry to win. As a (sort of) Brazilian who supports an English club, I know how people feel about it here, and it's quite obvious how they feel about it there. Here, when a team wins the Libertadores, everyone's thoughts seem to be divided on celebrating the trophy and celebrating the qualification for the club world cup. It's kind of a sad sight really, because the Libertadores is a much better and more relevant competition, but that's how it is. For European teams, winning the Champions League is the end-all be-all. When a team wins it, everyone involved celebrates only the trophy, no one even remotely thinks about the club world cup. Furthermore, they have even less reason to give a crap about the club world cup because it takes place midway through their season, which means they have a couple of extra matches and a hell of a long trip halfway through the season to worry about when they're usually just trying to get league games done - this is especially true for English teams, because besides not having a winter break, winter itself is usually the busiest period of the season, so by adding the club world cup in there it makes their whole schedule a mess.