Although large-scale quantum computers are not yet available, their future development poses a potential threat to the cryptographic foundations of cryptocurrencies. As an upper bound, we estimate that by the end of 2024, approximately US$ 586 billion in the Bitcoin network alone could be potentially exposed. We then examine whether investors are aware of this risk by analyzing their response to advances in quantum computing. Conventional cryptocurrencies exhibit negative returns and higher trading volume following such news, whereas a quantum-robust cryptocurrency exhibits positive returns. Our findings suggest that some investors are aware of quantum computing risks and respond by shifting toward quantum-resistant cryptocurrencies.