She was a gift from Putin.
She's a sleeper spy that paid off unbelievably well.
Why else was she involved in the money coming into the inauguration.
The money and influence he had. She wanted to become successful and knew he could help make it happen.
And get her anchor family into the country
I think it was all that and more. For instance his age...she knows that she will out live him and will reap "great rewards" when he dies. Also, it is all those other things...money, unlimited budget for fashions, money, prestige, money, social position, money...did I mention money? She would have married him if he a been a F....ing monkey.