Because whatever is a reality today, whatever you touch and believe in and that seems real for you today, is going to be—like the reality of yesterday—an illusion tomorrow.
I’m sorry, I’m too busy making Lobster Rage Fists at the idea of a stripper or an escort being happy at her job being considered unmarketable. Here’s the thing: you’re worried about an audience that doesn’t exist yet. The key to any character’s believability is the strength of their character and your writing, whether they’re a super spy or a fast food worker.
If you think you’re worried about this because your characters aren’t coming off as believable, a) it’s the first draft and that’s okay and b) take time off from plotting to work on your characters a bit more. Here is a massive resource list, check it out.
If you’re worried purely because of your character’s chosen professions, don’t. Those who would react negatively to your characters daring to like their jobs as sex workers aren’t people you want reading your stories anyway.
Fuck writing to be marketable. You don’t write to be marketable. You write because your character has a voice and needs to speak. Their story needs to be told. If someone has a problem with something in your story, that is not the writer’s fault. That problem is the reader’s.