I really didn't want to read this thread but feel I need to comment. I have name changed for this as I post often.
There is no way to justify prostituting yourself, that is exactly what escorting is.
I started escorting at 19 to pay the rent, very bad choice. I was under the illusion it was all okay, not much worse than one night stands, yadda yadda. What a complete load of shit.
If she does this, even if she "okay" with it for a while when doing it, it will come back and bite her up the arse, she will regret it. I learned this the hard way.
Although I made a lot of money and it was a lot, I charged a fair bit more than your friend and my clients were the nice dressed, well mannered types it didn't change anything. You are still there for the same reason, you are not looked at as a person, just a disposable fuck toy.
I find it hard to live with myself now, I contemplated suicide many times and am now completely broken as I will never be the same person I was when I was younger.
I'm posting this because if there's a way for me to let even 1 person know that it's not going to be the way they think it will then I will be happier.
I got smarter and unlike many unlucky people realised I was completely brainwashed.
If you let her do this, condone it whatever then it's you that deserves to be in her position as you could have saver her a lifetime of mental health problems (at the very very best).