Here's the thing, if you stay in the US as PR, the ordinary citizens will only view you as someone who has a Green light ( GC ) to stay in the US as long as you desire. If you're a citizen, you become one of them and most importantly, you get to elect the president i.e. vote. Even the Puerto Ricans can't vote. I still remember the Korean fellow ( Vtech shooter ) who got blasted for being able to buy a gun by none other than Glenn Beck who questioned the authority of that guy to buy the guns. I'm not saying that you should get the citizenship so that you could use it to unconditionally bag the rights of buying arms and do anything as such but provided that you're a genuine Nepali fellow who's here in the US to make a fortune, I'd suggest that you took the oath and became a US citizen! You've already stayed here long enough to prove that you want to live here all your life so why still choose to stay here as a guest instead a becoming an American?!