You are missing the point: no one should be placed in a position of having to earn a living at 15 (or younger) or not having access to food and shelter, good health care, education and/or job training. Being forced into such a situation while still a minor limits ones' choices for the rest of their lives.
Who do you think has said otherwise? And do you care only about those who have a viable option of sex work or also everybody else who lacks access to food, shelter, good health care, education, etc? An attractive person who can stomach sex work has an option those others do not.
Significant prostitution happens 'underground' no matter how legal it is.
That doesn't address the point. Nobody had claimed that decriminalized prostitution will mean zero underground prostitution. What it does mean is an option to do it above ground with the protections that comes with that. And taking away that option puts more people at risk. Does that concern you?
How about changing that market? How about eliminating that market?
How do you propose eliminating the underground sex market? Making all sex work illegal doesn't do that.
In my line of work, I am exposed to multitude of dangerous and infectious substances but I don't have or need a panic button because someone might decide to beat me or choke me or rape me.
And wouldn't you object if that safety was taken away by us branding you a criminal for doing your job?
And my employer pays for any medical treatment I might require if I am exposed to something that might cause illness or injury, as well as workman's comp. Those 'luxurious' brothels in Nevada don't provide that nor do any that I am aware of.
That can change. That is just a matter of regulation.
The fact that you see prostitutes as 'privileged' speaks volumes about you, and not about the realities of sex work.
Your judgement is not an argument, and you have not addressed the point that having the option doesn't mean one has to take it, and having an option to make good money where others lack that option is indeed a privilege.