Yeah, any clubs that will play in FIFA Club World Cup are best of the best club of each regions because they've a selection first. Since we're not really know with the club's power, there's a good chance of the underdog beat the favorite since it's got underestimated by many people.
It's better than bet on underdog where you're really know the league, example Nottingham Forrest vs Manchester City, I don't think any single person will bet Nottingham Forrest lol.
To qualify for FIFA you have be really strong team and won the matches so the teams that have their chances are playing well like we have seen small teams in this world cup also performing good defeating big teams.We can't say people will not bet on underdogs as they might also have potential but if you know about them.