They don't.
I don't know if someone said this exactly but if they did, either they dont know what their talking about or they're just talking to hear themselves speak.
The hand that feminists are trying to play is that sex workers are just fine, it's society that's fukked up.
While it's true that society is fukked up and Americans are so hypocritically puritanical that we'll never accept sex work as a legitimate way to make a living, the truth is a large number of sex workers are dysfunctional.
Sex work too often is a symptom of the dysfunction, not the other way around.
The well adjusted stripper, porn star, or prostitute is rare.
They tend to make choices that facilitate the dysfunction rather than seeking healing from it.
The actual sex work is terrible for someone with a fragile psyche, because no matter how you dress it up, one has to deal with the fact they're selling themselves as a product for someone else's use.
While I don't think sex workers should be persecuted or harassed for what they do, by the same token let's not lie to ourselves and pretend that sex work is the route to happiness.