There are women who may be born in money or reach success on the backs of broken relationships. Entering their thirties they appreciate they may never find a man to love them, never have children.
Many appreciate that a man falling in love with them is unlikely.
Some are unattractive, many have unpleasant personalities. No man of their status would chose to spend a minute in their company. In their own country they’d have to buy a low level man who was unlikely to stay with them, much less be faithful.
As the years pass they become more unattractive, more unpleasant.
The only way they will ever be in a marriage and perhaps have children is to pay for it.
Those who have money who come from 1st World Countries use the VISA, and potential citizenship, as currency.
The local is quickly schooled in how the game is played, for the rules are simple.