No experimentation necessary, it's blatantly clear that's the case.
that may be improved through deliberate practice
Perhaps. Or maybe it's just trying to distract yourself from reality through what are commonly accepted "values." Hard to know. I read all those studies about "happiness" coming from great relationships, and family etc...
None of them question why happiness is a virtue - it's as though it's implied that hedonism qua epicureanism is preferential. That's what I can't get past.