Though, the industry is aware of this and working on it. There is at least one company (Chia Network) where the on-chain language (ChiaLisp) is both capable and secure enough to allow for the sort of management needed to allow for self-custody to happen in a safe, sane manner. GUIs for this sort of thing aren't ready for the general public yet, but are definitely on the way.
People who "closely study mistakes and successes of the past" are in a very rare supply in the crypto space, and for a good reason: because people who actually closely study mistakes and successes of the past don't want to touch that space even with a 10-yard stick.
The reasons were spelled out in no uncertain terms 7 years ago in https://medium.com/@kaistinchcombe/ten-years-in-nobody-has-c... and followup here https://medium.com/@kaistinchcombe/decentralized-and-trustle... 17 years in, all those reasons remain the same.
Unless you're talking about people who are studying the mistakes and successes of crypto scams, and are working to refine them (the scams), then you can find a few.
So all you need to do then is learn a Lisp? That sounds worth the effort for most non-tech people...
Passwords, credentials and other high-risk high value intangible data are not associated with high-risk high-value AND our memory is not designed for random junk.
Maybe an anthropologist can study this phenomenon further.
We already have hints of that: our memory has evolved for thousands year to easily memorize places and spatial navigation, in thr past for food, water and danger. Today you go in a foreign place, just one visit and you know where everything is. At the same time, people can usually hold only ~7 concepts/numbers/objects in their head.
In memory competitions people leverage our spatial prowess with a technique called the memory palace, that was already used in ancient Greece and Roman Empire to recall anything, from bard tales to the Iliad and Odysseus.