I once briefly dated a very pretty Ukranian girl with poor English that had her own big pad in the NYC financial district. I would estimate her rent to be in the $3000 ballpark. She was always free during the day and most evenings.
Her explanation: “I nanny a few hours a week sometimes”. She would sometimes mention prostitution (not about herself) and get into this strange depressed state. I was finally certain of it and confronted her after she left her second phone turned on while with me.
When we parted ways she said she's addicted to the lifestyle but wished she could do something else. It was causing depression and drug abuse that I found out about later.
It’s easy to get addicted, mainly since the money is seemingly so easy to make. In time though, it ends up taking it’s toll and yet, it’s so easy. Look at Heidi Fleiss; she went from a perky and such to a madam and is now a meth addict.