Prostitution helps the prostitute financially in just the same way that any job helps the person who does it. Prostitutes get paid for what they do. This benefits them financially. The degree to which they benefit depends on the amount they are paid and the amount that they get to withhold from their pimp, escort agency, brothel, or other “boss.”
There are different levels of prostitution. The prostitutes at these various levels make very different amounts of money. The lowest are the streetwalkers who are the most visible prostitutes. They also tend to be selling the most hurried and squalid services and are accordingly paid very little. At the high end, there are the “call girls” who work for escort agencies (or, at times in today’s world, for themselves via the internet).
Prostitution can be financially beneficial to the prostitutes if they are not able to make more money at any job that seems more acceptable to them. Some prostitutes lack education or have drug problems. These things prevent them from holding down good jobs. Other prostitutes simply make a lot of money since they are “high-end” and could not make as much money at any “legitimate” job.