There might be an exhibitionist aspect to it, they want to broadcast their fetishes. They are central to their existence. In the same way people have hobbies like going to the gym, or dancing or visiting abandoned buildings, these people base their identities around their fetishes. They could save up and buy the maid dress, or they could get off on the idea of simps funding them and giving them attention.
Lucas was like siphyllis, aggressively unpleasant but possible to get rid of. Dong and the Dimitriadis dude are more like herpes, something we'll just have to deal with from here onwards. Embarassing, irritating, but not exactly a threat to our existence. I'll take my horrifying reacts for this unnecessary, grotesque metaphor.