I never lost access on my Bitcoin and Altcoins wallets And the following is what I do when join or need to use new wallet which didn't use it before, many of wallets have some guide on how you can use their services and state that they do not own keys only you own, so I read it carefully then following procedures to open wallet, while think of more than one areas/places which I see are safe to store my keys/mnemonic phrase that I only access those areas/places so I store those keys to multiple places which are arranged. this helps if I forgot one place of storage I go to another area. I believe It not easy if you store in three or more different places to forgot all those places that why I never lost access on my Bitcoin and Altcoin wallets
Those guides are really helpful the only problem is the lazy people who wouldn't read it and complains when they lose or got hacked because of their lazyness.
And it is really a good idea to back up our keys in order to secure it.
I have experienced it before my USB flash drive got lost with my keys on it luckily I have some back ups on my computer.