Well any one with the gift of the system can gain this much power easily which is injustice to others who worked hard all their life to just be overtaken by a fraud
Its a power fantasy. And if you actually know anything he isnt a fraud. Every hunter ever is using borrowed power. it is not theirs. It comes from the "rulers". Sung Jin Woo is essentially the Shadow Monarch's successor. The "System" isnt real. Its a way to adapt sung jin woos body to the immense power the shadow monarch has. Simply put, quite literally nobody in this show has power they have worked for. It is all borrowed or given to them. The rulers and monarchs got their power from the creator and every hunter get their powers from the rulers, while sung jin woo the exception gets his power from the shadow monarch and later becomes the shadow monarch once his body is strong enough for the full power of the shadow monarch.