Elon Musk, the richest person in the world, is on the record saying he is 'not often happy.' Somehow I doubt he'd give up half his wealth to double his happiness, though that's just a guess based on his other obvious character flaws ;)

My favorite book about this is "The Happiness Trap," because it makes the simple point that we didn't evolve to be happy all of the time. It makes a really good case for learning to live with the range of emotions and suggests ways of creating a contented/good/whatever life with what you've got.

Sometimes I wonder if he would be willing to give up half of his wealth to make everybody as unhappy as himself.