But what reason is there to cultivate this happiness-independent-of-circumstances if not in order to be happy? But if I do not wish to be happy, then I have no reason to cultivate this kind of happiness. It is like you are trying to tell me a way that I can get free oil for my car instead of having to buy it from the gas station, when I don’t have a car, but a bicycle (or maybe a skateboard?). I have no use for this source of free oil.

And of course the happiness from getting things I want doesn’t last; if it did, my happiness would cease to be a useful signal for others of what I want, and therefore the mechanism which modulates my happiness would cease to usefully serve its purpose, which would be detrimental regarding the goal of me getting more of what I want.

Your arguments are all assuming that I terminally value being happy, and without that assumption they have no foundation.