[malnourish]

I would imagine that people choose sex work even if they are not destitute.

For example, look at the American porn industry or "high-end" call girl/escort scene. Often, it seems, these women (and men) come from means, or at the very least, not squalor.

Poor sex workers are of course more open to exploitation, but you would still find sex workers in developed nations with high social welfare (Australia, for example).