Why are some people so delusional?

I have a friend who isn't a bad person, but she says the most delusional things about herself sometimes.

For example, she's overweight and struggles with insecurities regarding her fat distribution, yet she recently just blatantly and seriously told me (with no prompt or context) that she's an "hourglass". Well, she's just... not. No offense whatsoever but she's so far from that body shape it's genuinely making me question her sanity.

Or she gets told she looks like (insert a very attractive character), idk why people around her tell her that, but she just believes it and gets so excited, although she genuinely looks the exact opposite of this person and I think she has to know it deep down. To be clear, I'm not just talking about mild relative differences, I'm talking the literal opposite nature of features.

She's not stupid either. She's a reflective and deep person. She has more self-awareness than most people I know. Looks-wise, she's very regular and average looking (no offense whatsoever). She is in no way remarkably attractive or unattractive, for that matter. All of which make it even more insane to me.

I know the intuitive explanation is that she's insecure or compensating, but this level of delusion baffles me, and the way others feed into it scares me.