Always and everywhere banking has faced precisely this problem, which is the original reason for bank regulation and deposit insurance-type backup.
If you encounter an unregulated or irregular market participant doing anything that looks like banking, buyer beware-- on average, over time, you're not getting your money back.
If you encounter an unregulated or irregular market participant doing anything that looks like banking, buyer beware-- on average, over time, you're not getting your money back.