Coinbase research chief says 6.51 million BTC could be at risk from quantum attacks

Coinbase research chief David Duong warned in a recent post that advances in quantum computing could expose legacy Bitcoin outputs and other address types, estimating about 6.51 million BTC (32.7% of supply) at risk based on data through block 900,000. He also cited BlackRock's May 2025 prospectus and government guidance targeting post-quantum migration by 2035.