Happiness is not in the mere possession of money; it lies in the joy of achievement, in the thrill of creative effort.
F. D. Roosevelt
Well no, money does not make one happy. But it is an indicator. Why you ask?
Well people who have a lot of money often have earned a lot of money. And they did this by having discipline and doing hard creative work over a long period of time (in many cases at least).
This long time of hard and creative work is what makes people happy. Building up things, creating things, that is what makes humans happy.
So someone can be happy without having money and someone can be happy with having lots of money. It would be wrong to say that most people who are happy have lots of money. But I think it is safe to assume that most people who have lots of money (-> earned lots of money) are in fact happy, because they felt achievement and joy.
It is a saying that not the one who can buy everything is the happiest, but the one who needs the least. I agree. And the one who needs the least is the one who has created more than anyone else: A modest human being that has turned down ego and greed to a minumum.
Work on things you love and by that work on yourself, your charakter, your body: That will bring you happiness! If money is involved: All right. If there is not much money involved: Fine.
Don’t go out there in search for money. If you want to succeed merely in order to get rich, I do not want to work with you.