Bitcoin is trusted by governments and monetary establishments. Outstanding buyers name it “digital gold,” and a few even declare it is higher than gold. Regardless of all this, Bitcoin nonetheless faces varied safety threats. So much has been stated just lately concerning the potential menace of quantum computer systems. Nonetheless, Professor Campbell Harvey of Duke College revealed one other concern: 51% assaults towards the Bitcoin community are comparatively low cost.
abstract
- If profitable, a 51% assault would enable an attacker to take management of the Bitcoin blockchain (or one other proof-of-work based mostly blockchain). To achieve success, an attacker should management over 50% of the mining hash fee, which comes at a value.
- Previously, Bitcoin Gold and Ethereum Traditional skilled profitable 51% assaults leading to coin theft as a consequence of double spending. All through historical past, the Bitcoin blockchain has remained safe from 51% assaults.
- In keeping with Harvey, to monopolize hashrate technology for per week, an attacker would wish to spend “solely” $6 billion, lower than 0.5% of Bitcoin’s market capitalization. Harvey supplied the potential of sensible use of such an assault.
Campbell Harvey, a professor at Duke College’s Fuqua Faculty of Enterprise, printed a paper centered on potential threats to Bitcoin. In his abstract, Harvey compares Bitcoin to gold, however outlines that Bitcoin faces its personal distinctive threats: quantum computer systems and, extra importantly, the potential of a 51% assault. He additionally acknowledges that Bitcoin has benefits over gold. For instance, he says that whereas “trendy alchemy” permits for the manufacturing of extra gold, the provision of Bitcoin can not exceed 21 million models.
learn extra: Quantum Countdown: How Bitcoin’s 15-year defend stands as much as its largest menace but
What’s a 51% assault?
Mining Bitcoin is dear and requires particular {hardware}, so miners haven’t got the chance to tinker with ledger information. Every node “votes” through its computing energy (hashrate) to validate transactions for brand new blocks, and the vast majority of miners vote for proper information. Miners depend on the integrity of the Bitcoin blockchain, so that they have an incentive to vote for proper information, which brings worth.
Nonetheless, as soon as half of the full hashrate within the system is managed by a single entity (both a person or a bunch of plotters), it has the facility to alter the data on the Bitcoin ledger. This permits malicious events to maneuver another person’s Bitcoin and basically steal their Bitcoin.
Though some have criticized Bitcoin for its low stage of decentralization, within the 16 years that Bitcoin has existed, nobody has succeeded in controlling the Bitcoin blockchain.
Within the early days of Bitcoin, mining was accessible to any PC proprietor. Nonetheless, as a result of mining is predicated on competitors and requires the luckiest miner to have the next hashrate stage than most of their rivals, computer systems, and even GPUs and FPGAs, shortly grew to become out of date for mining. In 2013, the primary ASICs (units specialised for Bitcoin mining) appeared available on the market. Bitcoin mining quickly became a multi-million greenback business, requiring vital funding and gear full of whirring ASIC units. In October 2025, Bitcoin mining issue reached a brand new excessive.
Bitcoin mining issue has been adjusted:
150T at +5.97% (new ATH).
It is good to see costs rising to offset the strain on hashprice. pic.twitter.com/3qrdKirgnR
— Javier Hermosa (@JavierHermosa21) October 2, 2025
This makes hacking Bitcoin with a 51% assault a tough and costly job. As the problem of mining will increase, the price of a 51% assault additionally will increase yearly.
Campbell Harvey’s Discovery
51% assaults are pricey, however the price is just not unimaginable. Networks like Bitcoin Gold and Ethereum Traditional have suffered a number of 51% assaults since 2017. In every particular person case, greater than 1 million cryptocurrencies had been stolen. In August 2025, the Qubic mining pool claimed to have captured over 50% of the hashing energy of the Monero community.
learn extra: Monero in bother: Kraken freezes deposits, Qubic positive aspects 51% hashrate
Professor Harvey calculated the prices and concluded that it could price “solely” $6 billion to dominate the Bitcoin blockchain for one week.
“{Hardware} is the largest expense, about $4.6 billion at present costs. It could price $1.34 billion to construct the info middle, and about $130 million per week in electrical energy to run the {hardware} and preserve the info middle. In complete, a weekly assault would price about $6 billion, or 0.26% of the full worth of the Bitcoin community.”
This examine is predicated on the next indicators:
- Annual manufacturing of Bitcoin is 164,363BTC
- Vitality consumption is 166.4TWh
- Whole price: $12 trillion
- Whole power price is $8.4 trillion
- Whole price per unit is $73,000 per BTC unit
Harvey identified that if the 51% assault on Bitcoin was profitable, the value would drop considerably and hackers might nonetheless revenue from it and get better greater than $6 billion. Harvey estimated the every day quantity of BTC perpetual futures at $60 billion and the every day quantity of conventional BTC futures at $10 billion. Harvey believes brief positions in these markets earlier than a 51% assault couldn’t solely return the $6 billion, but in addition generate vital income for the attackers. Harvey added that the motive will not be profit-related.
However critics of Mr Harvey’s warnings argued that establishing such a large-scale mining operation would take years and wouldn’t be ignored. Greater than that, it could be tough to brief promote such a lot of BTC whereas the 51% assault continues. It’s because there’s a excessive chance that the trade will flag the operation as market manipulation and disallow it.
Commenting on Harvey’s analysis, Matt Prusak, president of American Bitcoin, informed Bloomberg, “My view is that financial feasibility undermines the 51% concept. I dwell in the actual world and I am not frightened.”
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