What I know from news articles is that some of them openly "escort", like some traditional porn stars did more quietly. The fame on the screen can be brand-building for the even more lucrative in-person work.
As one said in a quote, regarding AI threat and crumbling economies: "The oldest profession will be the last profession."
If some of them want to move to the US right now, from currently healthier countries, one reason may be that social inequality means there are many deep-pocketed customers able to pay 5 figures for a weekend experience.
The decline of the US means that there will be increasingly fewer deep-pocketed customers able to pay 5 figures for anything.
Those who come to the US with enough money on the bank will have access to a lifestyle and experiences that are becoming more and more exclusive, which makes for great content for the peasant class to consume on their phones.