I'm not sure if this had been asked before. This is just an example of some odds that I saw recently Fighter A (1.30) vs Fighter B (3.65). With this obviously, Fighter A is the people's champ and Fighter B is the underdog.
Regardless of who is bigger and undefeated record, let's say you have no idea who these fighters are because the names can't even be read like Ulshrkubyki vs Ykwehgyfvbh. If you only have $10 left in your sports betting account, would you go for the champ which you can only earn $3, or go for the underdog which if he got lucky can triple your money?
I can correlate this with a recent cricket match that is played b/w India and Pakistan on 24 Oct 2021 at DUBAI (ICC T20 Worldcup). India was hot favorite or you can say people champs while Pakistan was underdog. The odds are 1.4 for India and 2.8 for Pakistan.
In the match, Pakistan completely outclassed India and beat them very easily. Those who bet on Pakistan have a party that night. The point is you have to understand the situation that who is a strong candidate for winning.