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 continues to be going through numerous safety threats. Currently, rather a lot has been mentioned in regards to the potential risk from quantum computer systems. Nonetheless, 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.
- Prior to now, Bitcoin Gold and Ethereum Traditional went by profitable 51% assaults, ensuing within the theft of cash by double-spending. All through historical past, the Bitcoin blockchain has been protected 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 doable 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 doable 51% assault. He additionally acknowledges that Bitcoin has its benefits over gold. For example, he mentions that “fashionable alchemy” permits the manufacturing of extra gold, whereas Bitcoin’s provide can not exceed 21,000,000 items.
Learn extra: Quantum Countdown: How Bitcoin’s 15-year protect faces its greatest 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 rely upon the Bitcoin blockchain’s integrity, which provides 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 ability to alter the data within the Bitcoin ledger. It’s going to permit dangerous 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 relies 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 grew to become out of date for mining. In 2013, the primary ASICs (gadgets specialised for Bitcoin mining) hit the market. Quickly, Bitcoin mining changed into a multi-million-dollar trade, requiring a lot funding and amenities stuffed 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 value 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 value will not be unthinkable. Such networks as Bitcoin Gold and Ethereum Traditional suffered a number of 51% assaults after 2017. Every one among them resulted in a single million plus price of crypto stolen in every separate case. In August 2025, Qubic mining pool claimed it acquired 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 heart construct would require $1.34 billion and the electrical energy to run the {hardware} and keep the information heart about $0.13 billion per week. All advised, a one-week assault would price about $6 billion, or 0.26% of the bitcoin community’s whole worth.”
The analysis relies on the next metrics:
- Bitcoin’s annual output is 164,363 BTC
- Vitality 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 value drop, and hackers may nonetheless revenue from it and earn rather more than $6 billion again. Harvey estimated BTC perpetual futures every day quantity at $60 billion and traditional BTC futures every 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 might 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 situations of an ongoing 51% assault could also be arduous, because the change will in all probability flag an operation as market manipulation and received’t let it.
Commenting on Harvey’s analysis, Matt Prusak, president of American Bitcoin Corp., advised Bloomberg: “My angle is that financial feasibility kills the 51% thesis. I stay in the actual world, and I’m not involved.”
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