In 2014, the founder of an Estonian bank bought 250,000 ETH during the Ethereum ICO for $75,000, then lost the mnemonic phrase. Today, it's worth $400 million. Keep money on an exchange, and you're afraid the exchange might collapse. Store it in a wallet, and you're worried about theft or losing the mnemonic phrase. Making money in crypto is hard, and keeping it safe is even harder.