Please, I did not wrote that I never experienced happiness, neither that it is illusory. I am just playing devil's advocate here, the comment started with a "What if".

The reply from ordinary got my intent right: maybe it is right that happiness is limited but sadness is not.

I think we could strike a parallel with perfection. Let's think about bowling. From the DSM-5 point of view, happiness is scoring a "clean game" with all strikes, i.e. the lack of mistakes. Isn't this the same as "happiness is the absence of disorders"? You can win a bowling game even if you make few mistakes, just as you can live a successful life with some small minor disorders.

As you can see, perfection is very limited and corresponds to a single value: zero mistakes.