It's not actually that hard. People who prove they cannot manage their BI are required to participate in a managed BI program. The individual can chose from any/all licenced managers (or an individual/family member willing to accept the responsibility) who provide varying levels of service for a specified Percentage of your BI.

Maybe an efficiency apartment with groceries delivered for 80%. Maybe a bunk in a dorm and a meal ticket for 50%.

Even an individual who can't manage their own money can still chose a service based on their needs.