Yes, they're definitely self-sustaining at a pre-1980 or so level. They have raw materials, abundant energy, the ability to feed themselves, and a decent IQ pool to pull from to design and manage what they need.
But they still need precision machine tooling, optics, semiconductors, etc to exist as a post-1980 economy.
But they still need precision machine tooling, optics, semiconductors, etc to exist as a post-1980 economy.