Buying it from a doubtful source is the mistake they do in that case. Get it from the real source and you won't have such a problem. If you bought ledger nano from "some guy" then you could lose all that you have, but if you buy it from ledger directly and not from some random stranger, the problem drops a lot smaller.
Bought a hardware wallet from the third party or unofficial store is similar like asking a stranger to create a web wallet for you where he's already know your seed phrase and private key, it just his choice to rob your coins or not. Hardware wallet is the most safest storage because it's almost prevent from any malicious virus and keylogger which can steal your coins. People are careless for not buy a hardware wallet when they have a huge amount of money on their web wallet or exchange.