"the tribe can fully sustain itself"

That's called a subsistence economy. It has downsides, such as very high rates of violence and other preventable deaths (like death during childbirth).

One could imagine trying to solve these problems, but all the solutions sound more like dystopia rather than utopia.

In any case, there is a fair amount of unsettled land. You can probably buy some or even squat, and try to make your own tribe.