There is also a possibility that the hardware itself could not be working anymore after some years. Replacing a new hardware wallet is not easy because you can't just buy it anywhere, most often you need to order it abroad which will cost you some money if the shipping fee is expensive.
If replacing a hardware wallet is cost-prohibitive, then I'd guess that you don't have a whole lot of crypto stored on it--or that you seriously don't have enough reserve cash or crypto to spend on such a contingency. The cost of buying a new Ledger or Trezor or whatever HW wallet you use is kind of a minor issue when we're talking about "being your own bank" on a grand scale.
Also, keeping your seed phrase or other form of backup safe is also kind of a small, if not trivial, problem. A seed phrase engraved or stamped on a piece of metal just needs a safe place to be kept in, no?