paper wallet – A paper or manuscript wallet for storing Bitcoins?

Most people I've talked to are convinced that a hardware portfolio is the safest place to store your Bitcoins. But I'm not sure I know it's not safe to create offline keys on an uncompromised blank system and write them on paper (two copies at two safe places). Of course, someone could steal the keys. But looking at the material portfolios, I see these risks:

  1. Seed words must be written – subject to theft
  2. If me or someone else wants to use the key in 10 or 15 years, the firmware will be out of date, the solution could be hacked or the problem might not be to find a safe computer with the same hardware. a USB port or accept the key. It reminds me when I want to get the movies of 20 years of cameras.
  3. It is more difficult to hide the stick itself more than a seed only a seed / key. If a criminal finds the stick, he could force me to distribute the seed.
  4. If it's not open source, I need to trust the manufacturer. For example. key selection may not be random. If the manufacturer chooses very few 10 million private keys, I will not realize it, but it could take back all Bitcoin credits from customers after a few years.

What do you think, what is the best hodl strategy for storing coins safely?