Since every individual carries out any job to earn money, he practices prostitution to all intents and purposes. Selling your sex organ is no different than selling any other part of your body, like your voice, brain, muscles, and more, just to get money.
the practice or occupation of engaging in sexual activity with someone for payment
Yeah, gotta agree that prostitution is something different, something more specific, and something not mixed in every work existing (climbing in work ranks through sexual favors is another matter).