Bitcoin vulnerable to quantum attacks as microtransactions surge

Coinbase’s 2026 outlook estimates that between 6.5 and 6.9 million BTC – roughly one‑third of all coins – are stored in address types (legacy P2PK and reused wallets) whose public keys are exposed on the blockchain and could be compromised by a sufficiently powerful quantum computer. Analysts warn that once such computers become available, they could forge signatures and steal the funds, prompting calls for post‑quantum cryptography upgrades.

CryptoQuant’s June 2026 analysis shows daily Bitcoin transactions exceeding 800 000, with about 80 % of them under 0.01 BTC. The surge is driven largely by non‑payment data protocols that use the OP_RETURN opcode (runes, ordinals, BRC‑20 tokens, etc.), which generate many tiny transfers. This activity inflates the mempool and could raise fees for time‑critical payments, even as overall price momentum remains weak.