They have no choice. We sent 16,000 troops to conquer their island and bring it into our imperial holdings in 1898, and have wasted no dollar or muscle in trying to squelch any and all national independence movements ever since then. Roughly that same number of troops maintains that occupation to this day, "overseeing" the island and controlling our interests in the Caribbean from Fort Buchanan in the territorial capital of San Juan. It's honestly not all that clear why the US is so obsessed with keeping the territory, but your tax dollars pay for it and your soldiers are ready to lay down their lives to keep it. Blaming a conquered people for "choosing to live" under imperial domination is fucking absurd. I assume what you really mean is that you want PR citizens to stay on the island and never emigrate to the mainland, but that is no more reasonable. We claim their bodies and homes as our plenary property, and even so you want to deny them the most basic rights of the citizen, free transit within their own country? Fuck that.