Because the models need more money to maintain an attractive appearance. They can not deny themselves visiting expensive beauty salons and buying designer clothes. To meet with someone like Melanie, you need to earn a lot of money 
Their expensive lifestyle is definitely one of the reasons. But in order to remain in the limelight, they needs some powerful connections as well, especially if the models are in to their mid 30s and 40s. A model without any political connection will never get any attention from the media, no matter how much beautiful and attractive she is.
I agree. In order to meet such a smart model as Melanie, you need not only to earn a lot of money, but also to be a famous politician or show-man. Melanie is different from the rest by some kind of family, mind, ability to create coziness.
To her credit, she has adjusted to her new life pretty well. And for the past many years, she has supported Trump as much as she can. Even during the POTUS campaign, she played a very important role.
