My suggestion is to just ban specific regions or countries and you can cut 80% of this fraud. I'm not going to name those countries outright but you should never ever be launching globally until you have these safeguards in place. Once you are known to be vulnerable to a certain scheme, it quickly becomes known in that region/country. Again and again I'm reminded why high trust societies remain high trust and why low…
Accept crypto for those countries, it doesn't have chargebacks and helps those vulnerable to the financial system.
But this QJE article[1] argues there's a ceiling to how far things scale. Concluding that the cost to keep a decentralized network secure scales with its total economic value. So while there is immediate value to it's user, it might not scale well, and can't replace a country's financial system anyway because securing it at a sovereign scale would just be more expensive.
[0]: https://www.mdpi.com/1911-8074/17/10/467 [1]: https://academic.oup.com/qje/article/140/1/1/7824430