Passion no question.
Passion they are looking for a fix for you.
If money is there game they will want me as a returning customer.
Same reason I don't look for a mechanic (or any trade) motivated by money.
As far as the post about doctors making a max of $50K, I personally know lots and LOTS of doctors and medical students (I play basketball with people from the medical college here weekly) that are drvien by nothing more than the passion to be a doctor. Sure they enjoy the money...actually most dont as they are so far in debt from school or the normal pay as an early graduate that they don't have $$, but they wanted and WANT to be a doctor first and foremost to help people.
Ask ANY pediatrician.... they get paid the worst, have the worst hours and arguably the worst patients why they do it.
Now anesthesiologist? (woohoo! Spelled right on the first crack!)... thats a different story.