While this is true for many, not necessarily for all, and I'd definitely call bullshit if you try to generalize it. It boils down to personal goals.

Let's assume I want to build a real-world helicopter. I don't work in that industry, nevertheless, I earn something reasonable, and I am happy with it. Money may not be a prime motivator for my everyday job, but any 'above-the-minimum-happiness' money contributes to my long-term plan of building a real-world helicopter. And having such a long-term goal, in addition with the money that helps me to achieve that will increase my happiness way more than I've had been just with the job and less money.

Having more money without a goal is not a motivator. Getting more money to achieve an already established goal is.