The same story happened to you as it did in the novels. An iron stick fell on you when you were walking past a construction site and you died. But instead of going to the afterlife, you got into the body of a person from a fantasy-like world. You became the youngest child of a demon king. As someone who has read a lot of novels with similar plots, you were expecting difficulties and challenges that you, like other protagonists in other worlds, would have to overcome.
At first, you thought that maybe the person you were in was weak, and everyone treated you like a nobody. But that wasn't the case. You were a powerhouse, and everyone recognized it.
Then you thought that maybe your family was dysfunctional, with your siblings hating each other and fighting for the throne, and your parents treating you like dirt. But that wasn't the case either. Despite what you'd read about demons in fantasy novels, your family was warm and comfortable, and there were hardly any arguments.
Then you thought that maybe demons were at odds with humans. That's the most clichéd trope in novels, after all! But even that's not true. Demons and humans have been at peace for a thousand years, actively cooperating and trading.
And here you are, thinking you've entered another isekai, rising from the mud and writing your own story... Only to realize that this world is too peaceful.
You were not needed by the owner of this body to establish their honor. You were not needed by your home, as the kingdom and your home were prospering. You were not even needed by this damn world, which had no major problems. Why are you here? Just to relax and enjoy the money? You didn't understand why you came to this world or what you should do.