No shit? I could never have guessed. 
It would not be fraudulent if you stayed married long enough to get your own citizenship in progress. You would need a job. They do allow legal immigration of foreign nationals, still.
... for now, anyway.
It is fraudulent to get married to an American citizen just to get a green card. It has to be a real marriage, or at least the immigration people have to believe that it is real.
I have a friend who fell in love with and married a man from Germany. They met at Yellowstone National Park while he was vacationing there.
He was able to come here with a fiance visa before they got married, but he had to find someone to sponsor him, to be responsible for his debts should he incur them, because of course he did not have a job before he came here. For some reason, it could not be her. She got her ex-husband, of all people, to do that for her fiance. They had to answer some fairly intrusive questions from the immigration people after they were married before her husband could get a green card. He never tried to become a citizen, but he could have if he had wanted to. He would have had to give up his German citizenship to become an American citizen and he didn't want to do that.
