Unschooling.

I think unschooling can only really work if a child grows up in an environment that is full of daily interactions with many different adults engaged in interesting, challenging, and productive activities. These adults must be ready to include the child as a helper in those activities, or at the very least, allow them to observe and explain what they’re doing. The child should have ample resources to work on projects of their own, and the environment should have very little in the way of passive distractions and entertainment. There must be a strong expectation that the child contributes to and is part of the family activities and the upkeep of the household. Additionally, the child should have opportunities to take their interests outside the household, finding their own ventures or mentors. This was the environment that John von Neumann grew up in and though I don't think it created his genius I think it was necessary for his genius to flourish.

I think less than that, and unschooling is going to waste a lot of the child's time and potential, potentially leaving them passive and inept. While I do think children have natural instincts towards learning and improving themselves, those instincts evolved in the context of tribes and villages where everybody was involved in the constructive activities of life and society on a daily basis, and the child faced clear expectations from those around them.