This story is actually in the lower echelon of isekai, for abusing the plot-device of "torturing the MC for absolutely no fucking reason".
How it happens? Well, "Let's force the MC to choose every single bad decision he could've taken when it comes to his evolution-path, for reasons, every single time."
At around chapter 50 of the WN, it starts to really scrape at one's mind...At chapter 70~80, it becomes insufferable. Becoming a "plague" or "calamity" whatever dragon is where it all begins to fall apart.