It's not leatning curve that's difficult. It's the mindset. We all know how important it is to use password managers online, but most web surfers are still scare of them. It's the basics Internet hygiene and they failed in it.
Discussion
I think the average person is entirely capable of learning self-custody - even multi-sig - quite easily. The average person is just not really interested in learning anything on the fly with real stakes on the line.
I agree that this is not the general public's fault. This is on the bitcoin community in general (the social influencers in particular) for not more strongly pushing the general public in the direction of learning in a risk-free Testnet environment.
The tools are there and they are awesome. One example is
https://padawanwallet.com is risk free testnet bitcoin wallet to learn self custody and how to transact Bitcoin.
There should be no excuses. Bitcoin community is building constantly.
Prople are just ignorant. We can't force them into Bitcoin.