I care about wellbeing, but only second to pain. I’d definitely press a button maximizing happiness if it didn’t cause individual unhappiness worse than it cured. Doesn’t that make sense?
On second thought, two equally happy people > one and likewise with unhappiness. Maybe it doesn’t make sense after all. Or it’s a mix of a moral guideline (NU) and personal preference?
And this is why destroying everything in existence doesn’t seem obviously evil (not that I’d act on it...)