I think of it as, money can't buy happiness, but poverty can create unhappiness. I do think it's important for most people's happiness to get to a point where they can earn enough (at a job they don't hate) to never have to worry about how they're going to pay next month's bills or whether or not they can afford everything they need from the grocery store. Having to worry about stuff like that is a constant source of stress that wears away at whatever happiness someone does have in their life.

Beyond that level of income, whatever it is, people don't necessarily get happier, but they at least have more resources to work with. Depending on the person, and depending on whatever tradeoffs are made to get that higher income, they might figure out how to turn more money into more happiness, or they might not. That's more dependent on what makes an individual happy.