If AI optimists are correct, and AI can increase productivity across the board, tax revenues go up. Not rocket science.

Governments don't have a business model. They don't need to make a profit. (Also, debt doesn't work the same way for the federal government that it does for a business or even a US state.)

see, for just one take on this, https://www.ucdavis.edu/magazine/why-federally-funded-resear...