I created a new wallet.dat on a dedicated, secured machine with Bitcoin Core.
Then I encrypted it.
Then I sent my "fortune" of coins to it.
Then I backed the file up by putting it on all my disks on my normal PC as well as offline disks.
I even added it to Bitcoin Core on my normal PC, so it now lets me switch between my unencrypted "hot"/"live" wallet and the encrypted "cold" wallet in Bitcoin Core in a very neat manner, allowing me to always look to check that the coins are still there in the "cold" one.
Since I'm afraid to death of losing the encryption password, I did not write it down on physical paper and stick it into the fireproof safe (it could still burn, or get dissolved from water leaking in, or get seized/stolen under gunpoint). Instead, the password is PARTIALLY in various text files backed up on all storage devices I have, including instructions for how to input the rest of the password, which is based on "things that I know very well but others would struggle to guess or find out", such as past pets' nicknames and things like that.
I thought and worried for years before finally coming up with this scheme. To me, it seems like the only sensible solution, having very carefully looked into those hardware wallets and all other (known to me) ways to secure your coins.
My question is: is my "cold" wallet really "cold" if it's literally lying around on my Internet-connected Windows 10 machine, albeit in encrypted form and never decrypted on that machine? Or does it have to always be offline, even if encrypted, to be considered "cold"?