Governments and monetary establishments depend on Bitcoin. Respected buyers name it “digital gold” and a few even declare that it’s higher than gold. Regardless of all this, Bitcoin nonetheless faces a number of safety threats. There was lots of discuss recently concerning the potential risk posed by quantum computer systems. Nonetheless, Professor Campbell Harvey of Duke College revealed one other concern: the relative low value of a 51% assault on the Bitcoin community.
Abstract
- If profitable, a 51% assault offers attackers management over the Bitcoin blockchain (or one other proof-of-work primarily based blockchain). To achieve success, attackers should management greater than 50% of the mining hashrate, which is dear.
- Prior to now, Bitcoin Gold and Ethereum Basic suffered 51% profitable assaults, leading to cash being stolen by means of double spending. All through historical past, the Bitcoin blockchain has been secure from 51% of assaults.
- In accordance with Harvey, to dominate hashrate manufacturing for per week, attackers would wish to spend “solely” $6 billion, which is lower than 0.5% of Bitcoin’s market capitalization. Harvey offered a doable sensible use of such an assault.
Professor Campbell Harvey of Duke College’s Fuqua College of Enterprise revealed an article devoted to potential threats to Bitcoin. In abstract, Harvey compares Bitcoin to gold, however highlights that Bitcoin faces particular threats: quantum computer systems and, extra importantly, a doable 51% assault. He additionally acknowledges that Bitcoin has its benefits over gold. For instance, he mentions that “trendy alchemy” permits the manufacturing of extra gold, whereas the provision of Bitcoin can’t exceed 21,000,000 items.
Learn extra: Quantum countdown: How Bitcoin’s 15-year protect faces its largest risk but
What’s a 51% assault?
As Bitcoin mining is dear and requires particular {hardware}, miners wouldn’t have the chance to change the ledger information. Every node “votes” by means of computing energy (hashrate) to validate transactions in new blocks, and most miners vote for the right information. Miners are motivated to vote for proper information as they depend upon the integrity of the Bitcoin blockchain, which provides it worth.
Nonetheless, as soon as half of the system’s complete hashrate is managed by a single entity (an individual or a bunch of conspirators), it has the ability to alter the data on the Bitcoin ledger. It’ll enable unhealthy actors to maneuver different individuals’s bitcoins, successfully stealing them.
Whereas some criticize Bitcoin for its low stage of decentralization, nobody in Bitcoin’s 16 years of existence has managed to achieve management of the Bitcoin blockchain.
Within the early days of Bitcoin, mining was accessible to any PC proprietor. Nonetheless, as mining relies on a contest the place the luckiest miner will need to have a better hashrate stage than most rivals, computer systems and even GPUs and FPGAs rapidly turned out of date for mining. In 2013, the primary ASICs (specialised units for Bitcoin mining) arrived in the marketplace. Quickly, Bitcoin mining turned a multi-billion greenback trade, requiring lots of funding and services filled with whirring ASIC units. In October 2025, Bitcoin mining problem reached a brand new excessive.
Bitcoin mining problem simply adjusted:
+5.97% to 150T (new ATH).
The nice factor is that the value is rising to offset the discount in hash worth. pic.twitter.com/3qrdKirgnR
— Javier Hermosa (@JavierHermosa21) October 2, 2025
It makes hacking Bitcoin utilizing a 51% assault a tough and costly job. As the issue of mining will increase, the prices of a 51% assault enhance annually.
Campbell Harvey’s findings
Whereas a 51% assault is dear, its worth will not be unthinkable. Networks equivalent to Bitcoin Gold and Ethereum Basic suffered a number of 51% assaults after 2017. Every of them resulted within the theft of over one million cryptocurrencies in every separate case. In August 2025, mining pool Qubic claimed to have obtained greater than 50% of the hash energy on the Monero community.
Learn extra: Monero in hassle: Kraken freezes deposits, Qubic will get 51% hashrate
Professor Harvey calculated the prices and concluded {that a} week of dominance on the Bitcoin blockchain would value “solely” $6 billion:
“{Hardware} is the most important expense, about $4.6 billion at present costs. Constructing the information heart would require $1.34 billion and electrical energy to run the {hardware} and preserve the information heart about $130 million per week. In complete, a one-week assault would value about $6 billion, or 0.26% of the overall worth of the bitcoin community.”
The analysis relies on the next metrics:
- Annual Bitcoin manufacturing is 164,363 BTC
- Vitality consumption is 166.4TWh
- The overall value is 12 billion {dollars}.
- The overall value of vitality is 8.4 trillion {dollars}.
- The overall value per unit is $73,000 for 1 BTC unit
Harvey famous {that a} profitable 51% assault on Bitcoin would trigger a extreme worth drop, and hackers may nonetheless revenue from it and get better nicely over $6 billion. Harvey estimated every day BTC perpetual futures quantity at $60 billion and every day standard BTC futures quantity at $10 billion. Harvey believes that opening a brief place in these markets earlier than a 51% assault may generate large income for the attackers, along with returning $6 billion. Harvey provides that the rationale might not be associated to income.
Nonetheless, critics of Harvey’s warning argued that establishing such a big mining operation would have taken years and wouldn’t go unnoticed. Greater than that, promoting that a lot BTC beneath circumstances of a continued 51% assault could also be tough, because the trade will possible flag a commerce as market manipulation and never enable it.
Commenting on Harvey’s analysis, Matt Prusak, president of American Bitcoin Corp., advised Bloomberg: “My angle is that financial viability kills the 51% thesis. I stay in the actual world and I do not care.”
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