I think people do it for attention sometimes or an excuse for not having things done in life. And it makes them feel important.

I don’t understand why someone who doesn’t have actual diagnosis would claim that they do but I think the reasons above are why.

“I have anxiety“ sometimes means they get nervous at times like everyone else, “I have OCD” sometimes means I like my house clean-so do I and no I don’t have OCD, “I have PTSD” could mean 100 different things etc etc

I agree that it’s sickening but there is nothing you can do. I ignore it

There are people who like to exaggerate or fake physical illnesses too, not just mental. Attention seeking and getting out of things. We have somebody at work who when confronted about work not being done, claimed she had cancer and saying she’ll go on medical leave. She later denied she ever said it and claimed she said something else, we aren’t deaf though and it was a group of us and she was causing us problems with her work not being done.

She did it two years in a row. Both times when annual report and date analysis was due. Go figure