Would you be opposed to a sole proprietor offering loans at 200% apr?

The people who are going to take those loans because they can't get one at 150|100|50|whatever% are going to have a huge challenge, if they are even (blood from a stone) able to.

And while you as the lender may "enforce" repayment with guns and violence, you can only hurt someone so much, and the dead don't repay loans. You can't visit that violence on family and friends, because that is a crime, even if in the most wild west environment you're being allowed to enforce repayment from the lendee with violence. And in the end, while beating the shit out of someone delinquent may be psychologically satisfying to your psycopathic or sadistic ways, you're still out your principal.

The wise lenders will rapidly find the sweet spot between repayment and default.