The costs of a typical suburban house in the US can be broken down as: 50% land, 25% materials, 25% labor.
By living in the wilderness rather than in a developed area, the 50% cost of land gets cut substantially. By using Chilean workers, the 25% cost of labor is also substantially reduced.
Remember that Chile's GDP per capita -- while high for South America -- is only 2.5x that of China.
Even if land, construction, and labor costs are considerably less, it's still something.
Additionally, he's involved in quite a few hobbies which can be expensive. I'm not saying he has (or needs) tens of millions of dollars but has to have some.
By living in the wilderness rather than in a developed area, the 50% cost of land gets cut substantially. By using Chilean workers, the 25% cost of labor is also substantially reduced.
Remember that Chile's GDP per capita -- while high for South America -- is only 2.5x that of China.