Bitcoin is trusted by governments and monetary establishments. Respected traders name it “digital gold,” and a few even declare it’s higher than gold. However all these, Bitcoin remains to be going through numerous safety threats. Recently, quite a bit has been mentioned concerning the potential menace from quantum computer systems. Nonetheless, 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 offers 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.
- Up to now, Bitcoin Gold and Ethereum Basic went by means of profitable 51% assaults, ensuing within the theft of cash by means of double-spending. All through historical past, the Bitcoin blockchain has been secure from the 51% assaults.
- In response to Harvey, to dominate within the hashrate manufacturing for one week, attackers would wish to spend “solely” $6 billion, which is lower than 0.5% of Bitcoin’s market capitalization. Harvey supplied a attainable 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 necessary, a attainable 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 largest menace 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 knowledge. Every node “votes” through computing energy (hashrate) to validate transactions in new blocks, and the vast majority of miners are voting for proper knowledge. Miners are motivated to vote for the right knowledge as they rely on the Bitcoin blockchain’s integrity, which supplies it worth.
Nonetheless, as soon as half of the full hashrate within the system is managed by a single entity (an individual or a bunch of plotters), it has the facility to alter the information within the Bitcoin ledger. It is going to permit unhealthy actors to maneuver different folks’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 achieve management over the Bitcoin blockchain.
Within the early days of Bitcoin, mining was accessible to any PC proprietor. Nonetheless, 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 turned out of date for mining. In 2013, the primary ASICs (units specialised for Bitcoin mining) hit the market. Quickly, Bitcoin mining changed into a multi-million-dollar business, requiring a lot funding and services stuffed with buzzing ASIC units. 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 through a 51% assault a tough and costly activity. Because the mining problem goes up, every year the prices of a 51% assault are getting larger.
Campbell Harvey’s findings
Whereas a 51% assault is dear, its worth shouldn’t be unthinkable. Such networks as Bitcoin Gold and Ethereum Basic 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 bought 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 biggest expenditure, about $4.6 billion at present costs. The info heart construct would require $1.34 billion and the electrical energy to run the {hardware} and keep the info heart about $0.13 billion per week. All instructed, 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
- Whole price is $12 trillion
- Whole power price is $8.4 trillion
- Whole 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 far more than $6 billion again. Harvey estimated BTC perpetual futures each day quantity at $60 billion and standard BTC futures each day quantity at $10 billion. Harvey believes that opening a brief place on these markets earlier than a 51% assault may lead to excessive income for attackers on prime of returning $6 billion. Harvey provides that the motive will not be profit-related.
Nonetheless, 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 alternate will in all probability flag an operation as market manipulation and gained’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 stay in the true world, and I’m not involved.”
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