So lets say you do not have a U.S. citizenship but you spend a lot of time in the U.S. You buy products and create goods from them which you resell (say you build sheds out of wood or something of the kind). You have no employees and do all the work yourself. How much do you need to be making per year for it to be considered a business, which you would not be allowed to operate in the U.S. without citizenship or certain visas?