Citibank's latest report highlights the accelerating advancements in quantum computing as a significant threat to Bitcoin and other cryptocurrencies. The report identifies Bitcoin's reliance on ECDSA elliptic curve cryptography as a vulnerability, potentially allowing quantum computers to derive private keys from public keys, leading to asset theft. Analyst Alex Saunders notes Bitcoin's conservative governance and slower upgrade pace make it less adaptable to quantum-resistant changes compared to networks like Ethereum. The report estimates that 6.5 to 6.9 million BTC, valued at approximately $450 billion, are at risk due to exposed public keys, including some linked to early P2PK addresses and Satoshi Nakamoto. Citibank also warns of the "Harvest Now, Decrypt Later" threat, where attackers could store encrypted data now to decrypt it with future quantum capabilities. Despite these risks, Citibank remains optimistic about the crypto industry's ability to adapt through post-quantum cryptography and protocol redesigns, noting ongoing discussions around BIP-360 and BIP-361 proposals.