The available explanation is that for Japanese boys, sumo wrestlers are equivalent to superheroes, heroes, for people of Western cultures, perhaps top boxers or MMA fighters. It is only for us that they are seen as funny fat men in funny shorts, but at home they are famous athletes, they are highly respected and live in abundance.
What motivates people when they decide to become artists?
What motivates people when they want to get a dog?
Everyone is different and everyone has their own motives / benefits