There is a remote risk and exchanges can get hacked from time to time but it's just a factor you need to consider when trading crypto. To do business with Unlisted you need to keep your funds on the exchange. We use Kraken which is one of the longest standing exchanges on the planet and has never been hacked. They focus on security before anything else.
Having said that, in recent times people of high net worth have been taking funds out of the traditional banks and putting them onto crypto exchanges. Crypto exchanges don't have the "house of cards" exposure that banks have today to the derivatives markets and crypto exchanges are booming in growth cycles with lots of cash.
Generally speaking, if trading crypto by yourself (and not with Unlisted) you can also store your Bitcoin on hard wallets such as Trezor or Ledger. This moves Bitcoin offline to a USB-like storage device. Don't lose the device though, its like losing a bar of gold. If it's lost, it's lost.