In human terms, the dynamic nature of life manifests itself as desire. There is always something we want.
The truth is that we don’t ultimately all agree on what constitutes happiness, or pleasure, or justice, or other forms of being excellent to each other.
Judging right and wrong is just a matter of our personal feelings and preferences.
Life is a process, defined by activity and motion.
- Sean Carroll (2016) The Big Picture: On the Origins of Life, Meaning, and the Universe Itself
Happiness is a state. States don't exist, except when we're kidding ourselves.
There are things I care about - a lot. I want the biosphere to survive, relatively intact (except for snakes). I want every human to have a home (preferably neat and tidy). Truth matters a lot to me. The list goes on. There's no way to justify the list. No first principles that can withstand scrutiny.
Happiness is nice, but it's not the be-all/end-all. No way to justify that either.