That is very true, they store their funds in centralized exchanges and custodial services because they think they do not have what it takes to be their own bank, despite all the events that has happened with exchanges, they still believe that some exchanges are too big to fail.
Having more than one backup is great, but what's most important is the location where you store these backups, it has to be in different locations and these locations have to be safe. In other words, if you have two locations and you only one of them is considered safe, it is better to have only one backup in the safe location.