there are known whales in the industry of crypto/digital currency who doesn't use web wallets they prefer desktop wallet, own private keys and very own wallet.
It has not much to do with just whales, a lot people here sit on a potentially very valuable amount of coins. Everyone with a properly functioning brain and common sense knows that everything depending on a third party is something you should avoid if you care about your coins. In some cases there is no way to avoid using centralized services, like an exchange you do your trading on, but that's just a temporary practice. Most people nowadays have seen the importance of having a proper form of cold (offline) storage, which is why hardware wallets are in extreme demand right now. Funds at all times should remain disconnected from the internet, so even a desktop client isn't enough.