I think the best way to secure your wallet is to...

1. Generate new addresses from a formatted computer that is never going to be connected online.
2. Encrypt these addresses into password-protected .rar file (I don't think .rar file can be cracked, I believe it is very very secure).
3. Burn this .rar file into multiple copies of high quality DVDs (I recommend Verbatim's AZO DVDs).
4. These addresses will only be used as cold storage and transfer is done only when necessary.

Example, I generate 10 addresses and cold-store my bitcoin, ethereum, and erc20 tokens in them.
Say I have 100 BTC and generated 10 addresses.
I transfer 10 BTC to each of the addresses.
If I want to make an unavoidable transfer, I use only one of the 10 addresses.
If one of the addresses, once used, gets hacked, the remaining 9 addresses will remain safe.

With this method, I believe nobody absolutely need any hardware wallet like Trezor, Keepkey, Ledger, etc.