> Becoming a state would put enough regulation and oversight in place to make those problems go away, or at least put their corruption on the same level as a normal US state.

Becoming a state wouldn't fix the combined impact of NAFTA + the Jones Act, which alone is enough to wipe out the economy[0]. Corruption may be a cherry on top, but eliminating that doesn't solve the problem that there is simply no way they can export anything at a competitive rate, and that they also can't import things they need at reasonable prices either.

And becoming a state is in Puerto Rico's best interests, but it doesn't fix this problem either. Hawaii is suffering as well from the Jones Act - the difference is that Hawaii's economy was slightly less dependent on NAFTA-affected trade, and over 20% of Hawaii's economy comes from the military and national defense. So Puerto Rico is hit harder, but not for reasons that would be solved by statehood.

[0] NAFTA itself would not have been as much of a problem for Puerto Rico if it weren't for the Jones Act, so it's specifically the combination of both that's relevant.