Much unhappiness springs from the fact that we do not get what we want. We may feel that we do not get respect, appreciation or love from other people, so our life may become an exercise in seeking out approval.
Money can be linked into this "quest for happiness" too, because this is how, in modern society we feel we are appreciated. We do a job of work and that work is rewarded by money. If we are considered capable enough, we may get promotion and the extra money in our pay packets consolidates that promotion. So money can equate to love, acknowledgement, and respect.