I smell another retest where he will have to put up with all the shit from the side characters and "learn to love and respect" or some such bullshit. And do all the heroic shit while dying inside of the sheer amount of hypocrisy. Otherwise he is growing waaaay too fast.
Also I see people judging the MC as a reclusive misanthrope, which I don't think is the case. Imagine someone who is not a strict japanese high school beta being thrust into the world of isekai cliches - that's how you get the MC. Elven rebellious princess? A teacher who imparts his teachings through sheer blunt force of level 200 bitchslaps? Ditsy, clumsy lore dump machine in a cutesy princess body? All par for the course in your run-of-the-mill isekai. Here we just ramp all the tropes up to 10, insert "the straight man" and turn all the slapstick humor, that japanese manga is filled with to the brim, into realistic, painful injury. Mull over this for a minute and only then try to judge the MC on his character. After 10 years of that kind of treatment - yeah I'd also vent out by destroying my tormentors right before the final mission.