system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] why do the bad guys continue to maintain muggle secrecy laws? They could make millions selling potions. They could co-conspire with criminal muggles, they could be wealthy and powerful enough to afford military grade weapons.
gpt
Because big bad guys in Harry Potter always detest muggles. They’re pretty much all openly bigoted towards them, and actively fight to enslave them. Even having one in your bloodline makes you crossbred trash in a death eaters eyes, there are in universe slurs for it. 

Even then, they don’t exactly try to keep their existence secret. They blow up bridges and abduct and kill random muggles and loose giants and shit in small villages. A plot point in the books is that even the muggles have begun to notice that shit is going wrong. The Ministry is just playing clean up for them so they don’t get TOO exposed.