I'm not an expert on the rules for charities, but there are rules that specify some ratios for genuine charitable spending, overhead, management pay, and rules

I'm not an expert on the rules for charities, but there are rules that specify some ratios for genuine charitable spending, overhead, management pay, and rules re nondiscrimination, etc. As long as these regulations are strict enough to prevent gross abuse, requiring nonprofit orgs that accumulate endowments to adhere to those rules should be sufficient. But evidently those rules and the way they are enforced are not preventing gross abuses. More transparency about nonprofit finances would help guide reform. And that should include religious orgs.