Blockchain concentrates risks of rare intensity: financial, criminal, technical, environmental and systemic.
6.1Financial risk: volatility
This is the most immediate risk. Bitcoin has lost more than half of its value several times, including recently: from about $126,000 at the end of 2025 to $65,000-70,000 in mid-2026. Altcoins and memecoins amplify these swings even further, and most tokens launched end up at zero. The golden rule repeated by every regulator: never invest more than you can afford to lose, and beware of any promise of a guaranteed return.
6.2Criminal risk: scams, hacks and rogue states
The figures from the Chainalysis Crypto Crime 2026 report give the measure:
- Illicit addresses received at least $154 billion in 2025 (+162% in a year, inflated by sanctions evasion), while accounting for less than 1% of total transaction volume: the overwhelming majority of activity remains legitimate.
- $3.4 billion stolen through hacks in 2025, including $1.5 billion in the Bybit attack alone (February 2025), the largest digital heist in history, attributed to the North Korean Lazarus group. North Korea alone stole $2 billion in 2025.
- Scams (fake platforms, romance "pig butchering", rug pulls) are estimated at $17 billion in 2025; the FBI recorded more than 180,000 crypto-related complaints that year.
- The risk is also becoming physical: in 2025, France saw a series of kidnappings and extortion attempts targeting entrepreneurs in the sector.
6.3Operational risk: irreversibility
No bank to cancel a transfer, no customer service to reset a password. A lost private key, a wrongly copied address, a buggy smart contract (The DAO in 2016, the Ronin bridge in 2022: $625 million) and the funds are lost for good. It is estimated that several million bitcoins are unrecoverable forever. Irreversibility, the strength of the system, is merciless towards human error.
6.4Environmental risk
According to the University of Cambridge index (CBECI), Bitcoin's proof of work consumes an amount of electricity comparable to that of a country such as Poland or the Netherlands depending on the period, plus a material footprint (ASICs that quickly become obsolete). Nuances: the growing share of surplus or renewable energy used by miners, and above all the counter-example of Ethereum, which cut its consumption by about 99.95% by moving to proof of stake, proof that the problem is a design choice, not an inevitability.
6.5Systemic risk and the paradox of recentralisation
Terra, Celsius, FTX: 2022 showed that an ecosystem born against intermediaries had recreated them, opaque and unregulated. The paradox remains: mining concentrated in a few pools, trading in a few giants, stablecoins with two issuers (including Tether, long criticised for the opacity of its reserves). The Bank for International Settlements regularly warns about the risks stablecoins pose to financial stability, especially since their growing weight in US Treasury bills creates an unprecedented channel of contagion between crypto and traditional finance.
6.6Societal risks
- A generalised casino: memecoins, leverage and the gamification of trading expose a young public to brutal losses, an emerging public health issue.
- Surveillance: a public ledger is traceable for life; anonymity is largely a myth (pseudonymity), and on-chain analysis tools have become very powerful.
- Monetary sovereignty: dollarisation through stablecoins weakens the currencies of emerging countries and raises questions for Europe (see Module 7).
Going further: the library
French-language books and reports
Bitcoin, la monnaie acéphale
Favier & Takkal Bataille
CNRS Éditions, the French reference on Bitcoin.
Blockchain and the Law: The Rule of Code
Primavera De Filippi & A. Wright
Harvard UP, the law facing "code is law".
No Crypto. Comment Bitcoin a envoûté la planète
Nastasia Hadjadji
The political critique of the phenomenon.
L'Enfer numérique
Guillaume Pitron
The material footprint of the digital world.
Les crypto-monnaies
Landau report
The founding report (2018).
Publications on crypto-assets & the digital euro
ADAN & Banque de France
International books
Bitcoin: A Peer-to-Peer Electronic Cash System
Satoshi Nakamoto
Nine pages, the founding text (2008).
Mastering Bitcoin
Andreas Antonopoulos
The technical bible.
Digital Gold
Nathaniel Popper
The early days of Bitcoin.
The Infinite Machine
Camila Russo
The birth of Ethereum.
The Bitcoin Standard
Saifedean Ammous
The "Austrian" defence (partisan).
The Future of Money
Eswar Prasad
Digital currencies and central banks.
Digital Cash
Finn Brunton
The history of the cypherpunks.
Number Go Up
Zeke Faux
A major critical book.
Going Infinite
Michael Lewis
The FTX affair.
Attack of the 50 Foot Blockchain
David Gerard
A radical critique.
Sources
Chainalysis, 2026 Crypto Crime Report (chainalysis.com); Chainalysis, Crypto Theft 2025 (chainalysis.com); CoinLaw, Crypto Security Statistics 2026 (coinlaw.io); Cambridge CCAF, CBECI index (ccaf.io).
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