Sorry but if AI can build itself then it can run companies of size 3000 companies with a few people. Or even higher. What are the consequences?

When AI is a more effective capital allocator than NI it will drive capital into the accounts of whoever controls the AI, gaining them increasing decision making power over the economy and culture. Maybe those controllers will be human at first.

As has been mentioned in the sibling comment it already is.

Consequences are: financial crisis.