Nobody will have to learn this stuff, if the BTC economy develops there will be professional custodials for all levels. Eg. banks.
But the importance is that there is always the option to self-custody if you want to. With fiat you don't have that option even in theory. I think the option for self-custody is what makes BTC powerful alternative, not necessarily how widespread self-custody is going to be.
The stack of hundred dollar bills under my mattress disagrees with you.
You mean that if you store cash it will magically disappear once you hit a certain quantity or age?
One other area to learn about: security – while it’s true that you can move millions on yourself own, the risks of theft or accidental loss are why most people do not avail themselves of these theoretical options since they consider the cost of banking fees to be an acceptable trade off for the security and convenience of letting a professional handle those problems.