Non-custodial wallet or self-custodial wallet. You need to use a correct term.
I know all these terms. You can also call such wallet self-hosted.
A self-hosted wallet refers to a type of digital wallet that is hosted and controlled by the user, as opposed to being hosted by a third-party service
You can also search for it online to know that I am correct.
If possible, storing your backups at different locations.
This will be the best that can be done but I guess that most people will backup the seed phrase someone at there home. It can be in two or more locations but at the same home which is not safe enough.
As you will understand, someone who has so many bitcoins is more likely to have several houses or other places where he can hide copies.
But what about someone that does not have several bitcoin, not having more than 1 house and not want to lose his seed phrase? $0.1 BTC may be small to some people but big to some people depending on how rich they are. With your explanation, I think the rich people withore than one house are favoured.