Cryptocurrency

What it is, what it is not, and the risks that are unique to digital assets

9 min read Intermediate

"Bitcoin has gone from pennies to £50,000 and back to £15,000 and up again. It has made people rich and it has wiped people out. This chapter explains what it actually is, honestly, without hype in either direction."

For educational purposes only. Nothing in this chapter is financial advice. All figures are illustrative examples. Tax rules, account types, contribution limits, and regulations differ by country and change over time. Always verify current rules with official government sources or a qualified financial adviser before making any investment decisions.

What Is Cryptocurrency?

Cryptocurrency is digital money that operates on a decentralised network — no central bank, no government, no single company controls it. Transactions are recorded on a blockchain: a ledger maintained simultaneously by thousands of computers around the world. Change one record, and every other copy flags the inconsistency.

This makes the blockchain extremely difficult to tamper with. It also means there is no authority to call if something goes wrong — no customer service line, no FSCS protection, no ability to reverse a transaction sent to the wrong address.

The two most important cryptocurrencies

₿ Bitcoin (BTC)

Fixed supply of 21 million coins — ever. Digital scarcity enforced by code. No company behind it. Used as a store of value (digital gold). No smart contracts or programmability.

Ξ Ethereum (ETH)

Programmable blockchain — smart contracts run automatically when conditions are met. Powers most DeFi, NFTs, and Web3 applications. More complex, more utility, less scarcity than Bitcoin.

The Volatility Is Not Temporary

Bitcoin has experienced eight separate drawdowns of 50% or more since 2011. Not 10%. Not 20%. Fifty percent or more — meaning someone who invested at the peak lost half their money and had to wait years to recover. Some altcoins have fallen 90-99% and never recovered.

Bitcoin major drawdowns

2011

-93%

2013–14

-86%

2017–18

-84%

2021–22

-77%

Each of these was followed by a recovery — but the recovery took 1–4 years and many investors sold during the decline.

Risks That Are Unique to Crypto

⚠️ Exchange collapse

FTX — one of the world's largest exchanges — collapsed in 2022, taking billions of customer funds with it. Celsius, Voyager, and BlockFi followed. There is no FSCS equivalent for most exchanges.

⚠️ No underlying cash flows

A stock represents ownership in a business that earns money. A bond represents a loan that pays interest. Bitcoin represents... the expectation that someone will pay more for it later. There is no earnings growth to anchor the valuation.

⚠️ Regulatory risk

Governments can ban, restrict, or tax cryptocurrency. China banned it entirely. The US SEC is still defining which cryptocurrencies are securities. Regulation is uncertain and unresolved.

⚠️ Self-custody risk

If you hold crypto in your own wallet and lose the seed phrase, your funds are gone permanently. No recovery. This has happened to thousands of people.

⚠️ Altcoin risk

There are over 20,000 cryptocurrencies. Most were created to enrich their founders and have gone to zero. Even the top 10 from 2015 mostly no longer exist.

A Responsible Approach, If You Choose to Invest

There is no objectively correct position on cryptocurrency. It might become the future of money. It might be mostly speculative assets that eventually deflate. Reasonable people disagree strongly. What is not reasonable: investing money you cannot afford to lose, or treating it as a substitute for a diversified investment portfolio.

If you choose to hold crypto:

Keep it to 1–5% of your portfolio maximum — enough to benefit if it rises, not enough to be wiped out if it falls
Stick to Bitcoin and Ethereum — avoid altcoins unless you understand them deeply
Use a regulated exchange with proper custody (Coinbase, Kraken) — not obscure platforms
Consider a Bitcoin ETF (available in the US via BlackRock, Fidelity — easier, no self-custody risk)
Treat it as a high-risk speculative position, not a savings account

Questions People Actually Ask

Is Bitcoin a good investment?

It depends on your time horizon and risk tolerance. Over its entire history, Bitcoin has dramatically outperformed almost every other asset class. It has also had periods of 80-90% drawdowns that lasted years. If you would sell during a 70% crash, you will crystallise the loss and miss the recovery — which is the worst outcome. The honest answer is: it might be, but only if you can genuinely hold through extreme volatility without panic-selling.

What is the difference between Bitcoin and blockchain?

Blockchain is the technology — a distributed, immutable ledger. Bitcoin is one application of it. Ethereum is another. Many other blockchains exist with different properties. "Investing in blockchain" as a technology thesis is different from buying Bitcoin — you can do the former through technology stocks of companies building blockchain infrastructure.

What happened to FTX?

FTX was one of the world's largest cryptocurrency exchanges, founded by Sam Bankman-Fried. In November 2022, it was revealed that FTX had been using customer funds to prop up its sister trading firm (Alameda Research). When Binance pulled out of an acquisition, FTX collapsed within 72 hours. Approximately $8 billion of customer funds were lost. Bankman-Fried was convicted of fraud in 2023. The lesson: custody risk on exchanges is real.

Should I use a hardware wallet?

If you hold significant amounts of crypto (over a few thousand pounds), a hardware wallet (Ledger, Trezor) significantly reduces exchange custody risk. Your private keys are stored offline. The trade-off: if you lose the device and the seed phrase, the funds are permanently unrecoverable. "Not your keys, not your coins" is a genuine principle — but self-custody requires genuine responsibility.

Is cryptocurrency legal in the UK?

Yes. Cryptocurrency is legal to own and trade in the UK. It is regulated for anti-money laundering purposes by the FCA. Gains are subject to Capital Gains Tax. The UK does not have a Bitcoin ETF yet, but spot Bitcoin ETFs are available in the US. The regulatory framework is still evolving.

Key Takeaways

Cryptocurrency operates on a decentralised blockchain — no government or company controls it, and there is no consumer protection if things go wrong.
Bitcoin has had multiple 80-93% drawdowns in its history. This is not an anomaly — it is the nature of the asset.
Unique risks include exchange collapse (FTX), regulatory bans, no underlying cash flows, and permanent loss of self-custodied funds.
If you invest, keep it to 1-5% of your portfolio, stick to Bitcoin and Ethereum, use regulated exchanges, and only invest what you can afford to lose entirely.
There is no consensus on whether crypto is the future of money or a speculative bubble. Position sizing accordingly.