As of now, about 30% of all Crypto exchanges have been hacked. Would you leave your dollars in a bank when you knew there was a 30% chance of your money being stolen. Of course not! Besides, banks have your deposits insured, and nothing of the sort happens on Crypto exchanges.
What are your 'coins'? They are basically a string of characters that are made up of a public and a private key. I obviously have my coins stored in a cold wallet. That means that my coins continue to be on the respective blockchains. However, I CONTROL THE PRIVATE KEYS, because THAT is what you store in your wallet, meaning YOU, and only YOU, can access your coins on the blockchain.
I'm a trader, so I have to have x-amount of my 'bags' ('assets' in the legacy financial world) on exchanges. But I never trade more than 10% of what I have, and you can bet that the rest is safely stored in my LEDGER wallet.
(opens in new tab)