If a foreign lady has millions of dollars and is prepared to pay to migrate to the USA, I am very certain that she would have a large pool of potential partners to choose from. So, the question to the OP is: why you?
Because... You dont go to other people who are russian or from the same country... It would be suspisous
I think the question was: out of the millions of available Americans, why you? What's so special about you that you stand out from the rest? What would your potential spouse get from her payment? In other words, what makes you worth a few million dollars?