Buying the ledger from 3rd parties is fine... you just have to make sure you create a NEW seed upon receiving it. The ebay guy used a seed given to him meaning his private keys were already shared with someone else
No thats not the issue, the problem is that one of the chips in the Nano Ledger S is not secure, and can be modified by third parties.
If you're not confident to use hardware wallet then the best way to save all your long-term coin is a paper wallet and keep your private keys safely so that you can use them when you want in future. But for the regular usage, some of the desktop wallets like Electrum will do the best job.
Long back I planned to buy hardware wallet and after considering all the risks involved I dropped my idea of using hardware wallet and stick to my desktop wallet, paper wallet and for immediate access, I also use online wallets like XAPO and blockchain.
Hardware wallets are not as bad, as long as you have a backup of your private key (or preferably the seed). It's the easiest solution for people who are not tech savvy and don't want to play around with airgapped PC to store the desktop wallet, or to spend from the paper wallet when the time comes...
Hardware wallets are easy to use, but as everything else in life, it needs a basic understanding about the usage of it. I won't advice to someone (who is not confident enough to use a hardware wallet) to use a paper wallet because it makes the whole situation even riskier, e.g. the user keys in the private key on an infected PC online, not on a fresh OS installation on an airgapped PC...
I would suggest to use mobile wallets (Android or IOS, but without root or jailbrake) and hardware wallets for the beginners, if they want to secure their precious coins...