Caring about sustainability makes people especially miserable. Perhaps underscoring the point that pleasure is not the right goal...
I think it depends what kind of sustainability.. The sustainability of a state of being is probably a worthwhile goal..
The ecological kind, misery path for sure.. Until entropy can be reversed at least.
Along with these, sustainability. Imagine finding balance and peace, but seeing clearly that the tools and techniques used to get and stay there are temporary. Pretty unsettling. We have to get there in ways that are long lasting and unlikely to change radically.