Direct quote from the DSM, "Individuals who feign dissociative identity disorder do not report the subtle symptoms of intrusion characteristic of the disorder; instead
they tend to overreport well-publicized symptoms of the disorder, such as dissociative
amnesia, while underreporting less-publicized comorbid symptoms, such as depression.
Individuals who feign dissociative identity disorder tend to be relatively undisturbed by
or may even seem to enjoy "having" the disorder. In contrast, individuals with genuine dissociative identity disorder tend to be ashamed of and overwhelmed by their symptoms and to underreport their symptoms or deny their condition. Individuals who malinger dissociative identity disorder usually create limited, stereotyped alternate identities, with feigned amnesia, related to the events for which gain is sought. For example, they may present an "all-good" identity and an "all-bad" identity in hopes of gaining exculpation for a crime."
https://cdn.website-editor.net/30f11123991548a0af708722d458e476/files/uploaded/DSM%2520V.pdfFurthermore, if you look into the history of multiple personality disorder you'll find many women came out after the book turned movie Sybil become popular claiming to have multiple personalities.
Would also recommend, if you can, that you read "Sybil Exposed" by Debbie Nathan. She explains how Sybil was coaxed into believing fabricated abuse and that she made up the personalities to please Dr.Wilbur.
It's more than likely that DID, if it is real, is rare and most people malinger with it because they can benefit from being the snowflakes they truly are.