This is too simple of a take. The vast majority of prostitutes are not adult, willing, un-coerced independent contractors who take a short-term engagement. The money is made by the drug-supplying pimps and organizations that groom minors or prey on people who have no other way to support their habit. This is not moral and very different from the theoretical concept of prostitution.
That's not true in my experience. I've had friends who worked in or adjacent to the industry in several countries.
While there are obviously significant numbers of minors involved and some workers forced into it, the majority are not. Most are just struggling financially and trying to support themselves and/or families. Many are single moms. Many well over 18.