You say "redefine what happiness is", but I'm not sure there's any "re"-definition necessary, it can just be about how you define it. I wouldn't say that the things you mention (satisfaction, purpose, etc.) are alternatives to happiness, but rather that they're particular forms of happiness. And maybe the hedonism of the heroin addict is another form.

I'm not entirely sure it's incorrect to say that the heroin addict's life isn't a valid and desirable form of happiness in theory. The problem is that in practice pursuing that type of happiness has a high risk of plunging into extreme unhappiness. The same might be said of various other forms of happiness that we see as at least somewhat less objectionable. For instance, people who do BASE jumping may find a sense of satisfaction and fulfillment from doing it, but still many people might view that skeptically as a path to happiness, because again it has high risks of bad outcomes.

I tend to think in terms of aiming for what I call "robust happiness", which means a form of happiness that's resistant to changes in circumstance, and in particular to the awareness of other people's happiness. When you're happy in a way where you can look at other people being happy and not wish to have their life or their form of happiness instead of yours, your happiness is robust in a certain sense.

I like your idea of robust happiness and it being robust against comparison.