Ex-Google engineer warns quantum, miner risks to Bitcoin

Patrick Shyu, an engineer who worked at Google and Meta and later built a large online audience, outlined two threats to Bitcoin’s long-term security in a recent video. He said he sold all his bitcoin holdings in June 2026 after the price fell about 50% from roughly $126,000 in October 2025 to the low $60,000s in the summer of 2026.

Shyu described the first concern as a shrinking security budget for miners. He noted the block subsidy, the new-coin reward miners receive, halves roughly every four years and currently stands at 3.125 BTC per block. The subsidy is scheduled to fall to 1.5625 BTC at the 2028 halving. Shyu called attention to the fact that about 95% of bitcoin has already been minted and said transaction fees have not risen enough to replace subsidy income.

He pointed to mining-market data to show pressure on operators. Hashprice, a daily measure of mining revenue per unit of computing power, has been low, and miners absorbed an 18% hashprice drop in late June when mining difficulty rose by 7.15%. Shyu argued that if subsidy income falls and fees do not increase, some miners could turn off equipment, reducing the amount of computing power securing the network.

The second concern he raised is quantum computing. Shyu warned a powerful quantum computer running Shor’s algorithm could derive private keys from public keys that appear on the blockchain, exposing older addresses. Estimates for when such machines might appear vary; some researchers point to the early 2030s and others to the mid-2030s.

Developers and cryptographers have proposed technical responses. One proposal, BIP-361, lays out a three-phase soft fork to move funds to quantum-resistant addresses and to limit coins that do not migrate. Other engineering teams have suggested transaction methods designed to be resistant to quantum attacks using current protocol rules. Discussion and coding activity on quantum defenses have increased among developers.

Some academics have argued that mounting a practical attack on Bitcoin’s mining system would require impractical amounts of energy, describing the scale of resources needed in extreme terms. Critics of Shyu noted he has shifted positions publicly in the past and observed his warning came during a week of market moves in the opposite direction.

Shyu attributed his personal losses to excessive leverage and automatic liquidations after the price decline. He described the market as fragile but added he remains a long-term bullish investor. The 2028 halving and ongoing developer work on quantum migration remain key events that market participants and protocol contributors are watching.