It is not necessary for every single adult (or child - who will decide who is able to use the system? The concencus of the system will decide, so children (and the definition of children) will also likely be able to take part) to be interested in using the system for the sake of the system, or even at all.

People will be interested in whatever grabs their attention. If there is a cause group (external to the Matrix-8 Solution deliberation and voting concencus framework) which interests them they will join it. If they wish to effectively further the cause after free and open discussion in the cause group, they can optionally move it forward with actionable concencus in the Matrix-8 Solution mechanism.

It only takes a few committed souls to change the world - paraphrase if Margerat Mead quote