Let me try to summarise this so far:
Before he got summoned to another world, he was perfectly content with his life. He saw himself as a victim to kidnapping when brought to another world and just went with "All of this will be over if I just finish this" and bear through it for 10 years.
Only to be pissed for needing to restart again but the next time, he just speedrun through it and after each speedrun, he got better and better. Finally, he passed and is now participating in the carnival for some skills (I think).
As far as I remember he justifies his actions with "Early bird gets the worm" (I am sorry if I didnt word this correctly) which means he did all of this to gain advantage over others in the carnival.
I am the type who justify evil if its necessary for the greater good and I can see and kinda justify his actions before the carnival but not after.