Quantum computing poses a significant threat to the security foundations of existing cryptocurrencies. Most current cryptos, like Bitcoin and Ethereum, rely on cryptographic algorithms such as SHA-256 and ECDSA to secure wallets, verify transactions, and maintain consensus. Quantum computers, especially with Shor’s algorithm, could potentially break these cryptographic protections by solving problems that would take classical computers millions of years, in just hours or minutes.

If quantum computing advances significantly, it could expose private keys, allowing hackers to steal funds or forge transactions. This risk could shake investor confidence and cause a sharp decline in crypto values, especially for coins slow to adapt.

However, the crypto industry is already exploring quantum-resistant algorithms, known as post-quantum cryptography. Some newer blockchains are developing with these protections in mind. Additionally, hard forks or protocol upgrades may help legacy cryptocurrencies adapt before quantum computers become practically powerful.

In the near term, the risk is low since quantum computers capable of breaking modern encryption are still years away. But as the technology matures, the adaptability of each crypto project will determine its survival and value. In the long run, those that successfully transition to quantum-safe protocols will likely retain or even gain value.