Cryptocurrencies are increasingly embedded in the global financial and economic mainstream. One reason is that its security encryption, distributed ledger technology, or blockchain, is largely impervious to conventional cyber-attack or theft. However, thanks to Shor’s algorithm, cryptocurrencies will be exceptionally vulnerable to a future quantum computing attack. What makes crypto vulnerable to Shor’s algorithm is elliptic-curve cryptography, which applies to all distributed ledger technology. Based on our research, the overall cost of a major hack and devaluation of Bitcoin alone would equal $3 trillion plus. Fortunately, solutions already exist: post-quantum cryptography and quantum computing. Cryptocurrencies are here to stay. However, supporting crypto security with post-quantum cryptography or quantum cryptography will enable cryptocurrencies to remain a mainstay of the global financial system for many decades to come.