Bitcoin is trusted by governments and monetary establishments. Respected buyers name it “digital gold,” and a few even declare it’s higher than gold. However all these, Bitcoin continues to be going through varied safety threats. These days, lots has been mentioned in regards to the potential risk from quantum computer systems. Nevertheless, Duke College Professor Campbell Harvey revealed one other concern, specifically the relative cheapness of a 51% assault on the Bitcoin community.
Abstract
- If profitable, a 51% assault provides attackers management over the Bitcoin blockchain (or one other proof-of-work-based blockchain). To realize success, attackers should management over 50% of the mining hashrate, which is dear.
- Previously, Bitcoin Gold and Ethereum Traditional went by way of profitable 51% assaults, ensuing within the theft of cash by way of double-spending. All through historical past, the Bitcoin blockchain has been protected from the 51% assaults.
- Based on Harvey, to dominate within the hashrate manufacturing for one week, attackers would want to spend “solely” $6 billion, which is lower than 0.5% of Bitcoin’s market capitalization. Harvey offered a potential sensible use of such an assault.
Duke College Fuqua College of Enterprise Professor Campbell Harvey launched a paper devoted to potential threats to Bitcoin. In an summary, Harvey likens Bitcoin to gold however outlines that Bitcoin is going through its particular threats: quantum computer systems and, what’s extra essential, a potential 51% assault. He additionally acknowledges that Bitcoin has its benefits over gold. As an example, he mentions that “fashionable alchemy” permits the manufacturing of extra gold, whereas Bitcoin’s provide can’t exceed 21,000,000 items.
Learn extra: Quantum Countdown: How Bitcoin’s 15-year defend faces its greatest risk but
What’s a 51% assault?
As Bitcoin mining is dear and requires particular {hardware}, miners don’t have a chance to mess with the ledger information. Every node “votes” through computing energy (hashrate) to validate transactions in new blocks, and nearly all of miners are voting for proper information. Miners are motivated to vote for the right information as they depend upon the Bitcoin blockchain’s integrity, which supplies it worth.
Nevertheless, as soon as half of the whole hashrate within the system is managed by a single entity (an individual or a bunch of plotters), it has the ability to alter the information within the Bitcoin ledger. It’s going to permit dangerous actors to maneuver different individuals’s bitcoins, successfully stealing them.
Whereas some criticize Bitcoin for its low decentralization stage, nobody in 16 years of Bitcoin’s existence has ever managed to realize management over the Bitcoin blockchain.
Within the early days of Bitcoin, mining was accessible to any PC proprietor. Nevertheless, as mining is predicated on competitors the place the luckiest miner has to have the next hashrate stage than most rivals, computer systems and even GPUs and FPGAs rapidly turned out of date for mining. In 2013, the primary ASICs (gadgets specialised for Bitcoin mining) hit the market. Quickly, Bitcoin mining become a multi-million-dollar business, requiring a lot funding and services full of buzzing ASIC gadgets. In October 2025, Bitcoin mining problem reached a brand new most.
Bitcoin mining problem simply adjusted:
+5.97% to 150T (new ATH).
Good factor value is pumping to offset the hashprice squeeze. pic.twitter.com/3qrdKirgnR
— Javier Hermosa (@JavierHermosa21) October 2, 2025
It makes hacking Bitcoin through a 51% assault a tough and costly process. Because the mining problem goes up, annually the prices of a 51% assault are getting increased.
Campbell Harvey’s findings
Whereas a 51% assault is dear, its value just isn’t unthinkable. Such networks as Bitcoin Gold and Ethereum Traditional suffered a number of 51% assaults after 2017. Every considered one of them resulted in a single million plus price of crypto stolen in every separate case. In August 2025, Qubic mining pool claimed it received over 50% of the hashing energy within the Monero community.
Learn extra: Monero in bother: Kraken freezes deposits, Qubic grabs 51% hashrate
Professor Harvey calculated the prices and concluded that one week of domination on the Bitcoin blockchain would value “solely” $6 billion:
“{Hardware} is the biggest expenditure, about $4.6 billion at present costs. The information middle construct would require $1.34 billion and the electrical energy to run the {hardware} and keep the info middle about $0.13 billion per week. All instructed, a one-week assault would value about $6 billion, or 0.26% of the bitcoin community’s complete worth.”
The analysis is predicated on the next metrics:
- Bitcoin’s annual output is 164,363 BTC
- Vitality utilization is 166.4TWh
- Whole value is $12 trillion
- Whole power value is $8.4 trillion
- Whole value per unit is $73,000 per 1 BTC unit
Harvey famous {that a} profitable 51% assault on Bitcoin would trigger a extreme value drop, and hackers might nonetheless revenue from it and earn rather more than $6 billion again. Harvey estimated BTC perpetual futures day by day quantity at $60 billion and standard BTC futures day by day quantity at $10 billion. Harvey believes that opening a brief place on these markets earlier than a 51% assault might lead to excessive earnings for attackers on prime of returning $6 billion. Harvey provides that the motive will not be profit-related.
Nevertheless, critics of Harvey’s warning argued that setting such an enormous mining operation would have taken years, and it wouldn’t go unnoticed. Greater than that, shorting a lot BTC within the circumstances of an ongoing 51% assault could also be arduous, because the change will most likely flag an operation as market manipulation and received’t let it.
Commenting on Harvey’s analysis, Matt Prusak, president of American Bitcoin Corp., instructed Bloomberg: “My perspective is that financial feasibility kills the 51% thesis. I reside in the actual world, and I’m not involved.”
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