I'm not sure I understand the point of the original question. The question of whether we do what we do in life as a choice or because of the circumstances of our life or things in our past or whatever is a question you can ask about anything we do, not just this particular "hobby".
It's always a mixture of choice combined with significant pressure on us, based on our personality and circumstances, to make certain choices and not others.
If I'm a truck driver (I'm not), it is extremely unlikely that I'd still be doing the job if I won the $10 million lottery. I am doing it for the money, which I need to pay my bills. And I chose this job rather than others mostly based on who I am as a person. I could have done lots of other things, but who I am led me to this.
Same thing is true for escorts, or for streetwalkers. Most streetwalkers couldn't handle being an escort for a variety of reasons, based on who they are, or don't know that the option is available to them, and some might choose not to be an escort for their own personal reasons, again based on who they are.
I think most escorts would not be willing to be streetwalkers, some would. If the escort business were somehow wiped out, and it was a choice between being a streetwalker or finding another business entirely, most would go find a regular job. Another choice, based on who they are as a person.
There are an infinite number of potential choices, most of them are not possible for us due to practical reasons. I can't live on some other planet, I can't be Superman, I can't be Bill Gates son, I can't be an escort and have women pay me for sex since the world doesn't work that way. Even if it did, given the way the male body works I don't think many men could do the job. (Perhaps Viagra would make it possible, I'm not sure)
Of the choices that are available to me, my own personality exerts considerable pressure on me to make some and to not make others. I don't want to take a job at mcdonalds, despite whatever positives might come out of it, because then I'd be dirt poor. I don't want to steal for a living, even though I could no doubt think of plenty of ways to be successful at it, mostly for moral reasons. Who I am puts massive pressure on me to behave in what I perceive as a moral way.
Etc etc. I could go on and on, but I think the point is clear. We can all choose to do whatever we want, but the choices we make are strongly influenced by who we are. As this is true in every area of life, it is true for this particular "hobby".