Things are more complex than the Federal Gov gives PR,NYC,etc so much money and in return "they" have to give us this much in taxes.
PR has a Commonwealth Status,which probably gives them the best of both worlds in limited autonomy,financial arrangements,etc with the US.
They do not pay federal income tax,however they buy all,or most of their products,through the US and that puts $$ into our economy.So everything is not just taxes vs entitlement programs.
Politically,there is a "Resident Commissioner" who, looks out for their interests,lobbies,advices,etc ......................but has no vote in the congress of the US.
The PRcans have US citizenship,go into military service (more than a few.Actually a LOT of them go in the military),etc......but cannot vote in presidential elections unless they live in the US mainland.
There are stupid Puerto Ricans, and there are brilliant Puerto Ricans,as well as good and bad people.....just like everything else.Believe me.I know well that this is so.....and it is not PC,for those who always see positive comments as being PC!
In accepting a new state into the union, it comes down to what is good for for the "potential state" and the US.In other words a win-win situation, and neither the US or potential state is going to go into statehood unless there is a positive balance for both sides.