@Nessen You don't even realize that you answered yourself. "Most fat people can't leave their neighborhood". Well, we found the one that can. Moving on.
Like, seriously. MOST people are not billionaires. Which is why MOST books are not written by/about "the random dude accross the street", but rather about Steve Jobs. You know, the ONE dude who did become a millionaire.
I will also take the chance to educate you about something. 'Murican obesity aside, there are MANY reasons for being fat. "Being a fat fuck", aka, lazy bastard, is only one of them. Some are genetical (yes, it's a thing). I have happened to know a guy that ate fast food like no tomorrow and would NOT gain a single gram, and a guy who ate healthy and small sizes and would gain 3 kg.
Some people like to eat. If they like to eat, maybe they'll get fat. This guy may be using wyverns and rhynos to move around. Eats a lot, exercises little. Bam, he fat.
I do wonder where he gets the money, though. Maybe his family. "Suspension of disbelief" is easy enough to apply here. Plus, we're straying from what was your complaint. Your complaint was that only the MC recognized his "talent".
"This is something that should pique the interest of any person." You sure? Cause when I was in high school studying Japanese and reading manga, I was not the "interesting dude that learnt languages and cultures". I was the "fucking nerd otaku".