It is possibly less obvious to see how becoming a victim of prostitution at the age of 13 reduces one's skills and prospects at 20, but I assure you if you watch that documentary you'll have a better sense of it. Such girls are unlikely to have a home to go often, having often been thrown out, and it's very unlikely that they'll have made it through high school, without which job prospects are even worse. They are also likely to have become addicted to drugs, which, while they make their work less intolerable, grip their desires for a long, long time.<p>If your argument is that someone could have, consciously and without any coercion, decided to engage in sex work, then yes, it is possible, it is not even necessarily wrong. But to turn a blind eye to the situation because it might not be harmful in every case, where there is ample evidence that it is very harmful in many or most cases, strikes me as more hopeful ignorance than rational policy.