if there was a chance the op was genuine mn would lock the thread while they "investigated," they've done that before.
As to why people do these sorts of things, well generally it's because they can. After all this is the internet, you can be whatever you want to be, a high flying professional; have a husband and a couple of kids; a legal expert (judge flounce anyone?) or you can simply be going through a hard time which will bring you attention.
I used to be a moderator on another website, and I uncovered a troll who had made up at least four different personas over a period of about five years, all with debilitating disabilities/illnesses, had befriended people within the community she was part of (many of whom were vulnerable/going through similar), and just as the friendships deepened to the point of a potential meeting she killed them off, causing major upset/outpouring of sympathy on the site. And of course once her current persona had died, the only way she could gain more attention/adoration was to invent a new one. The worst of it is that I know who she is in rl, and while I've never met her, I know several people who have.
Lots of people say these people have mh issues, but tbh many are so calculating that I can't bring myself to have any sympathy for them.