The habits are easier to keep once you know what they cost
Every safety page on this site asks you to do something slightly inconvenient. Withdraw to a wallet you control. Read the transaction on the device rather than on the screen. Ask where a yield comes from before you take it. Those instructions are much easier to follow when you know what happened to the people who did not.
These are not horror stories and they are not written to put you off crypto. Each one is a post-mortem: what the company said, what was actually happening underneath, the sequence in which it came apart, and the signs that were visible at the time to anybody who knew to look. That last part is the useful bit, because the patterns repeat.
Figures are the best available public estimates. Legal outcomes were checked in September 2026 and several of these cases are still moving.
Exchanges that lost customer money
FTX
November 2022. The second largest exchange in crypto was lending customer deposits to the trading firm next door, and the trading firm had lost them.
Read the post-mortemMt. Gox
February 2014. The exchange that handled most of the world's bitcoin trading lost most of the bitcoin, slowly, over years, without noticing.
Read the post-mortemQuadrigaCX
January 2019. Canada's largest exchange said its founder had died taking the only keys with him. The keys turned out to be beside the point, because the coins had been gone for years.
Read the post-mortemYield, leverage and the returns that were not real
Celsius Network
June 2022. A lender that promised up to eighteen percent on deposits and told people to "unbank yourself", while quietly taking the risks that made those numbers possible.
Read the post-mortemThree Arrows Capital
June 2022. A hedge fund that borrowed from nearly every large lender in crypto without any of them knowing how much the others had lent it.
Read the post-mortemBitConnect
January 2018. A lending program promising about one percent a day, powered by a trading bot that did not exist.
Read the post-mortemCode and keys
The DAO
June 2016. The largest crowdfund in history at the time, drained through a bug in its own code, and the reason two Ethereums exist.
Read the post-mortemThe Ronin bridge hack
March 2022. North Korean operators took over most of a bridge's validators through a fake job offer, and nobody noticed for six days.
Read the post-mortemThe Bybit hack
February 2025. The signers checked the transaction on screen, saw a routine transfer, approved it, and signed something else entirely.
Read the post-mortemTokens built to fail
Terra and Luna
May 2022. A dollar backed by nothing except the promise that you could always swap it for another token, which worked perfectly until the moment everybody tried.
Read the post-mortemThe Squid Game token
November 2021. A token that rose more than twenty thousand percent in a week and that nobody was able to sell, by design.
Read the post-mortemOneCoin
2014 to 2017. A cryptocurrency sold to millions of people in dozens of countries that never had a blockchain, a coin, or anything else behind it.
Read the post-mortemThe scale of each one
| Case | When | What kind of failure | What it cost |
|---|---|---|---|
| OneCoin | 2014 to 2017 | Fraud with no blockchain at all | Estimated $4 billion or more |
| Mt. Gox | February 2014 | Exchange collapse | About 850,000 BTC, roughly $450 million at the time |
| The DAO | June 2016 | Smart contract exploit | 3.6 million ETH, about $60 million at the time |
| BitConnect | January 2018 | Ponzi scheme | Estimated $2.4 billion |
| QuadrigaCX | January 2019 | Exchange collapse | About 190 million Canadian dollars owed to 76,000 customers |
| The Squid Game token | November 2021 | Honeypot rug pull | About $3.3 million, and a total loss for every buyer |
| The Ronin bridge hack | March 2022 | Bridge exploit | About $625 million |
| Terra and Luna | May 2022 | Algorithmic stablecoin collapse | About $40 billion of market value in under a week |
| Celsius Network | June 2022 | Lending platform collapse | About $4.7 billion owed to depositors |
| Three Arrows Capital | June 2022 | Hedge fund collapse | About $3.3 billion owed to creditors |
| FTX | November 2022 | Exchange collapse | About $8 billion of customer money missing |
| The Bybit hack | February 2025 | Cold wallet compromise | About $1.46 billion, the largest crypto theft on record |
Four habits, drawn from all twelve
Hold your own keys
Every exchange failure here was survivable by anybody who had withdrawn. That is the single highest value habit in crypto.
Self custodyTwoVerify on the device
Bybit lost $1.46 billion because the signers trusted a screen. A hardware wallet exists to show you what you are really signing.
Hardware walletsThreeAsk where the yield comes from
Celsius, BitConnect and Anchor all paid a rate nobody could source. If you cannot name who funds it, you are funding it.
How yield worksFourRun the checks that are free
The Squid Game token was detectable in seconds with a sell simulation. OneCoin was detectable by asking for a block explorer.
Token safety checkerGo through your own setup with us
Where your coins actually sit, who is holding them, and what would happen to them if that company stopped answering the phone tomorrow. Usually an hour, on a screen share.