very few, if any girls can charge more than 1600 an hour and most charge a lot less. also, none of them work on their own, they all have agents, just like in scenes. those agents take a percentage.
40,000 is possible, but probably a bit exaggerated. Maybe if a specific client was a huge fan of hers, and kept her for 24 hours, including flight, hotel, shopping etc.
The suitcase pimp comment by Willie D is spot on. Also remember, very few if any of the girls (or guys) save any money. So any money made is constantly being used to catch up on old bills, warrants, rent, bail, what have you. The concept of saving money and looking ahead to the future is never done...by anyone.
I can speak personally to the fact that I saw a girl make 25,000 in 6 days after paying her agent. And that was doing like 10 jobs a day. So 40,000 would have to be a real anomaly and not the norm.
And by the way, prices are going lower and lower as more and more "porn stars" become available for escorting. Humaniplex has some girls on there for 300 bucks!