Sophie: Ok. It's basically on my mind every time I see someone use it, so I made my own version of "I'm happy because everyone loves me." to talk about it.
Main point being: I see a lot using it on its surface meaning of joy, but what we see in it is just - not that at all.
I think it's mainly contained within the phrase itself. It just sounds so sarcastic. Why would you say that? As in - you not only have to tell me you're happy, and explain why. To my ears this sounds like: "I'm fine because everything is ok" Which should give a better idea of our view on this piece
You don't say something like that because you're fine or happy. To me this sounds like coping, this sounds like masking. This sounds like something you'd say to get someone asking how you're doing off of you. Which ... we're too painfully familiar with not to see it this way.
So - while I there is no issue with using "I'm happy because everyone loves me." in a positive way - I can't help but to have it feel wrong to me... like it's missing something when I think of the original.