If you lose your private key for your crypto wallet, then you will not be able to access your BTC. Similarly, if someone else discovers your private key, that person can access your wallet and clear out your BTC so be careful! That being said, you could use a branded crypto wallet whereby quite often you do not need the private key because the wallet acts almost the same as an eWallet. You simply log in using a username and password and transact from within the wallet without ever needing your private key handy. However, if you do use one of these wallets, be sure you can trust the company!