Every person, who keeps coins on a private wallet instead of exchange is afraid of losing them. If it happens there is no way to restore them and the user loses access to every fund that was stored there.
Have you never heard of back ups or seed phrases? The entire point of hierarchical deterministic wallets is that they are easy and straightforward to back up. I don't let a third party hold a single satoshi for me, and I have never been afraid of losing my coins. Every piece of technology I own could break and my house could burn down, and I'd still have easy access to all my bitcoin if I needed it. You might want to have a read of the following page:
https://en.bitcoin.it/wiki/Seed_phraseThe risks of letting a third party store your coins - theft, hacks, phishing, poor security, hardware failure, exit scams, locked and frozen accounts, confiscated coins, surprise KYC, insolvency,
their back up procedures, the list goes on - far outweighs the risks of storing your coins securely yourself.