there is no love or mating test in marriage.
If all that is required is benefits, the marriage for immigration papers should be legal too.
Happens all the time. I know a friend’s nephew who married a Chinese woman in exchange for $10,000. He planned to divorce her as soon as she got her citizenship papers. Her sister who was already in the USA, paid him the $10,000 knowing he would divorce her. She was fine with that, as long as he married her and made her a US citizen. The only person in the dark was the mail order Chinese bride.
The last laugh was on him, though. He fell in love with her and ended up bringing over her parents, grand parents, extended family, and last I heard they were all living in the same house. So much for the best laid plans of mice and men.