Happy people are easily distracted. They are interested in many things. Because they don't have to shut out the world they welcome it in. Obsessives, specialists, tunnel visionaries, one trick ponies are all trying to lock the world out. they vainly hope that if they only drill deep enough the world will reveal all its mysteries. Strangely they discover that the narrower the drill hole the easier it is to drill...
But herein lies the problem, the conundrum- to get anywhere or learn anything you need to specialise. This will make you more obsessive. You'll find that though you're not exactly 'happy' a kind of dry fleeting happiness is available to you if you pursue with vigour your obsession. Other people and things become something to be co-opted or avoided. The world starts to bore you a little. You live only for doing more and more of what you narrowly do...
But if you flit from interest to interest you never really 'achieve' much- certainly money seems to be hard to find. You get a little bitter that the world doesn't recognise your talents, your effusive interest in so many things...and as you get bitter you find you are suddenly rather interested in only one thing- doesn't matter what it is- you find that doing this thing obsessively brings some relief, you don't need to worry about the world, success, money. You begin to specialise, drilling your own deep and solitary hole...
I would offer micromastery as one way out of this conundrum. You may specialise but also feed that specialisation with defined and easily mastered activities...I offer it...but I also know that everyone in this world has to find their own balance between obsession, happiness, polymathic interest.