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 numerous safety threats. These days, quite a bit has been stated concerning the potential risk from quantum computer systems. Nevertheless, Duke College Professor Campbell Harvey revealed one other concern, particularly 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 attain success, attackers should management over 50% of the mining hashrate, which is expensive.
- Up to now, 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 secure from the 51% assaults.
- In accordance with 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 supplied a potential sensible use of such an assault.
Duke College Fuqua Faculty 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 vital, 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 models.
Learn extra: Quantum Countdown: How Bitcoin’s 15-year protect faces its largest risk but
What’s a 51% assault?
As Bitcoin mining is expensive and requires particular {hardware}, miners don’t have a possibility to mess with the ledger information. Every node “votes” by way of 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 proper information as they depend upon the Bitcoin blockchain’s integrity, which supplies it worth.
Nevertheless, as soon as half of the overall hashrate within the system is managed by a single entity (an individual or a bunch of plotters), it has the facility to vary the information within the Bitcoin ledger. It’s going to permit unhealthy 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 a better hashrate stage than most rivals, computer systems and even GPUs and FPGAs rapidly grew to become out of date for mining. In 2013, the primary ASICs (gadgets specialised for Bitcoin mining) hit the market. Quickly, Bitcoin mining became a multi-million-dollar business, requiring a lot funding and amenities crammed with 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 worth is pumping to offset the hashprice squeeze. pic.twitter.com/3qrdKirgnR
— Javier Hermosa (@JavierHermosa21) October 2, 2025
It makes hacking Bitcoin by way of a 51% assault a tough and costly process. Because the mining problem goes up, every year the prices of a 51% assault are getting increased.
Campbell Harvey’s findings
Whereas a 51% assault is expensive, its worth is just not 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 value 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 hassle: Kraken freezes deposits, Qubic grabs 51% hashrate
Professor Harvey calculated the prices and concluded that one week of domination on the Bitcoin blockchain would price “solely” $6 billion:
“{Hardware} is the most important 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 preserve the information middle about $0.13 billion per week. All informed, a one-week assault would price 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
- Power utilization is 166.4TWh
- Complete price is $12 trillion
- Complete vitality price is $8.4 trillion
- Complete price per unit is $73,000 per 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 earn rather more than $6 billion again. Harvey estimated BTC perpetual futures day by day quantity at $60 billion and traditional BTC futures day by day quantity at $10 billion. Harvey believes that opening a brief place on these markets earlier than a 51% assault may lead to excessive earnings for attackers on prime of returning $6 billion. Harvey provides that the motive might 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 onerous, because the trade will most likely flag an operation as market manipulation and gained’t let it.
Commenting on Harvey’s analysis, Matt Prusak, president of American Bitcoin Corp., informed Bloomberg: “My angle is that financial feasibility kills the 51% thesis. I stay in the true world, and I’m not involved.”
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