IIRC you don't need to spend billions to get it trough FDA. That is the whole point of the generic. That the molecule is already approved and tested.

You don't need to spend money on phase 1-3 trials for safety and efficacy of the molecule but you do still need to spends tens of millions of dollars to prove that the generic drug you are manufacturing behaves like the original, within a margin of error, and that you can maintain that quality control in the future.