I feel like this doesn't do a good job establishing the MC. MC has structured his whole life around watching fights in the arena, spends most of his time doing it, and say it's a hobby. I don't think hobby is the correct translation for whatever it is he's doing. Most of his time seems to be spent on watching fights so it's hard to really classify that as leisure since it seems to be the majority of his time. Frankly, being an adventurer is closer to his hobby than watching fights.
We also aren't given enough insight to even understand why he likes arena fights so much. The fight he watched was 3 pages like, his commentary on it was extremely bare bones and basic in nature. It doesn't seem like he's fascinated by the technical aspects of fighting, fighter's potential, etc. Him being extremely strong actually makes this worse because now he's a guy that gets really excited over very low level fights. I just don't really get why he would be interested in this based on the intro. It feels kind of like the author just went "ok his hobby is watching people fight, that's the premise now move on I won't be going into more detail but i will bring up his hobby constantly."