I came across this horrific product on Amazon that people are actually buying and that puts them at risk of losing all of their investments. It is a large, physical coin with a private key etched into the back and the public key taped over said private key.
This is a terrible idea for one major reason. The fact that it comes with the private key already etched in, means that the manufacturing facility very likely knows these private keys and can access the funds that its customers decide to store on these “cold wallets” at any time they choose.
Even if for some reason you trust the manufacturer (and you shouldn’t), any individual employee working at the facility that has access to these coins before they are package (or access to the data used for the etching) could record the keys.
Also, while we are on the topic, do NOT purchase even reputable hardware wallets such as Ledger or Trezor from Amazon. Purchase direct from the manufacturer ONLY. Since anyone can sell on Amazon, you cannot trust that the reseller has not tampered with the device before sending it off to the Amazon warehouse.
Stay safe out there!