Primarily that acting as a prostitute? She's power leveling-- she gets a copy of a skill from every single person she's been sleeping with. There's pretty much no risk to her, in terms of disease, violence, etc. because, even at this point, she's already far more powerful than anybody in the city. It diverges a bit from the traditional isekai formula here, even the 'slow life' ones, because she doesn't want her cheat and doesn't want to utilize it (though, by keeping it on hand as an insurance policy, that in itself is using it...), instead wanting to just live as an ordinary person... albeit one that still semi-accidentally causes upheaval , like the introduction of chords and public girl talk.