If you come here on a visa to work as a waiter (which I really don't believe that)you work as a waiter, If you come here on a student visa or go to school on that visa, I would guess Visas have the amount of time you can stay here legally, then they expire....They might give you some extra time, but if you want to stay here legally you go back to your home country and apply or maybe get married to an american....then you still have to get another visa until you get your citizenship....you never said your friend became a us citizen.
People wait tables for years....in a good place you can take home 300 bucks a day. Better than 22 bucks an hour.
What? Do you think that it is necessary for a foreigner to leave the USA and get a new visa every time they get a new job? I genuinely don't understand your obsession with his friend. It sounds to me like this man came here for what we would consider a bad job, but it was still a step up for him. He later improved himself and moved up in the world. Now he is a financially independent and responsible guy with a good job. Isn't this what we should want our immigrants to do?