The Right Way to Use an NPC

I was a good person, so why did I have to transmigrate into a game world and become the Great Demon King!

I have no choice. This is what I have to do to you:

Gold coins? I'll take them! Main city? I'll burn it! Beauties? I'll collect them!

Witches? Black technology? Quantum weapons? A god-tier civilization from a parallel world?

Sorry, this is my territory! Get lost!