I've been working on a bitcoin course.
The first section will begin with 1942 to give an example of a closed society. FDR signed executive order 6102 in 1933, making it illegal for Americans to own gols.
By 1942, he imprisoned people for no other reason than their identity. Executive Order 9066 required people of Japanese decent to reprort to internment camps. The surviving Japanese people were awarded reperations in the 1980’s, but it was againat the law for them to own gold.
Imagine if the Japanese interned could have kept "illegal gold" as 12 memorized words.
The quest for electronic cash was an attempt to circumvent unjust laws written by totalatarian governments.
"Privacy is necessary for an open society in the electronic age."
Only 100% provable full-reserve, self-custudy solves the double-spending problem.
"Digital signatures provide part of the solution, but the main benifits are lost if a trusted third party is still required to prevent double spending. We propose a solution to the double spending problem."
Satoshi Nakamoto
Bitcoin: A Peer To Peer Electronic Cash System
In my opinion, that's why self custody is important.