I think we can all agree on this:
Happiness doesn't exist.
You cannot go to a part of the brain and say: "There! Thats some Happiness! He/She's got a whole lot of it! Must be a happy person."
Neither does Happiness nor Sadness exist.
Sometimes it's useful to talk about happiness, just like sometimes it's useful to talk about Fi. Your point is completely irrelevent to the discussion, which is ABOUT Fi.
Your analogy is inapplicable because Happiness can be described as both an abstract and a 'physical thing', there are many pleasure chemicals in the brain which are associated with happiness as one of their functions. We know not of a 'physical thing' which defines cognitive functions.
Yes we can talk about the abstract concept of Fi, but why waste the energy on all this negative shit people are posting about an imaginary thing when it can be a positive discussion about an imaginary thing?