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.
Yes, that's why it is advisable to buy it directly to the manufacturer, to avoid being hijacked or your hardware wallet being tampered by someone because they know it's going to be some crypto assets on those from individuals who are buying it.
It's easy to buy it from the manufacturer website, and then they also have some reputable stores as well carrying their products.
And I must say it's a must for every crypto enthusiast to have a hardware wallet.