In theory once you attract a big enough cluster of “tax hackers”, the government can then modestly increase taxes on these folks and that can be a high leverage thing once you’ve attracted a large revenue base.
But many of these people have sufficient mobility that you have to remain under the tax level of your competition. Most of them have no actual tie to Puerto Rico and would leave in a heartbeat if they found a better deal.
Not really. Puerto Rico has no real competition. It's the only place you can live inside of the US without paying federal income tax. If Puerto Rico were to raise its local tax, to say, 10%, it would still be the lowest overall tax jurisdiction in the US by a mile.