Title: On-chain analyst: Quantum-threat sell-off of Satoshi-era coins is scary — but not apocalyptic
On-chain analyst James Check pushed back this week against claims that a quantum-enabled attack on Satoshi-era Bitcoin would spell the end of the market. In an April 23 report titled “Selling Satoshi’s Stack,” Check argues the headline numbers driving the doomsday narrative confuse a theoretical maximum with the realistic sell-side pressure markets would face.
The numbers people cite
- Check’s report notes about 6.934 million BTC fall into categories whose public keys are exposed and could, in theory, be vulnerable to long-range quantum attacks. That total breaks down roughly as:
- 1.716 million BTC in Satoshi-era P2PK outputs
- 214,000 BTC in Taproot addresses
- ~4.996 million BTC in reused addresses
- Crucially, Check frames the 6.934M figure as an upper bound — not what would necessarily be dumped into the market.
Why the risk is smaller than it looks
Check emphasizes nuance. Taproot is relatively new, so many Taproot owners are likely active and able to migrate coins when a post-quantum path appears. Reused-address balances likely include large pools controlled by exchanges, custodians and ETFs — entities with incentives and the operational ability to upgrade security before a crisis.
That leaves the 1.716M BTC in Satoshi-era P2PK outputs as the primary true exposure — the “sunken galleon” many fear could be plundered if a cryptographically relevant quantum computer (CRQC) ever shows up.
How bad would a theft-and-sale actually be?
Even under a harsh assumption — that an attacker steals and sells the entire 1.716M P2PK balance — Check finds trouble but not total collapse. He compares that potential dump to multiple on-chain liquidity measures:
- Revived supply (coins dormant for 6+ months that move in a day) averages about 10,000 BTC/day in bear markets and can exceed 20,000–30,000 BTC/day during profit-taking in bull markets.
- Expressed another way, the full P2PK pot roughly equals 60–90 days of sell-side activity typical of bull markets or late-stage bear-market capitulations.
- Recent turnover also matters: over 2.3 million BTC changed hands between $60,000 and $80,000 since the Feb. 5, 2026 sell-off — 1.36x the P2PK balance — suggesting significant buyer depth at those levels.
Check’s blunt conclusion: “There is no doubt that a QC attacker selling all the P2PK coins would negatively impact the price. It probably creates a bear market. However, … it is nowhere near the ‘end-of-days’ fatal sell-side many quantum bulls in the debate seem to claim.”
Protocol-level mitigation: the BIP-360 “hourglass”
The report also touches on a proposed compromise in the BIP-360 debate: an “hourglass” rule allowing miners to include at most one P2PK output per block. With about 38,000 P2PK outputs on-chain, Check estimates such a throttle would take roughly 264 days to exhaust — a timeline roughly compatible with optimistic network-wide post-quantum migration plans.
Beyond market mechanics: a principles debate
Check is not dismissive of quantum risk. He explicitly calls for “the debate, development, and preparation” of credible post-quantum solutions. But he urges the community to separate two questions: the scale of sell-side market risk, and the normative issue of whether Bitcoin should preemptively freeze or otherwise alter property rights to prevent theft.
“To the folks who claim we MUST freeze the coins because of the sell-side, I’d encourage you to put some numbers to your claims,” he wrote. “Instead, the actual thrust of this debate is around the principles of what Bitcoin is.”
Market snapshot
At press time, BTC traded at $77,869.
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