Hmm, no not really.
I mean to say that people tend to think they are passionate for something when the prestige and remuneration for their work increases. I think of it as such; if lawyers and coles shelf stackers had the same social standing and remuneration, then the incentive to work harder for your money (ie. being a lawyer) decreases because regardless of what job you do, you will have the same social standing and remuneration.
So to answer your question, now I kinda changed my mind. Sort of, but I don't think money is the only thing. I think when a high paying job is coupled with prestige or social desire, then passion starts to kick in.
Furthermore, I think people are taught from a young age (through various media) to look up to doctors and lawyers from a young age, thereby making people aspire to be like them. We aren't taught to aspire to be the guy working at the milkbar because he doesn't have a high social standing or from what we can see, a high income (although he may).