What exactly is happiness, moods and states of the mind?
I was always under the impression that happiness was our default setting, our buddha nature. If we remove "blow away or extinguish" all the labels, bindings, and habit energies that collect what is left is happiness. True Happiness is the default state we experience when we extinguish the fires that cause suffering. This cessation of suffering can also be described as complete peace. 

It is a great wealth because it is the only thing that can bring us true liberation.