Actually, many entrepreneurs are driven by passion. You got to have lots of it to walk away from a steady paying job and start your own business, slave from morning till night, even when you sleep you're thinking of your cashflow, no salary for two years or more, etc.
If you're a wedding photographer, your passion is in making people look good in pictures, and the belief that you can give them something better than what's on the market, that you can make your clients happy. Because if you don't have this passion, you're going to be wondering why the hell are you slaving away night and day when you can go to some corporate job.
In other words, the majority of entrepreneurs are not driven by thoughts of an IPO, of being bloody rich. Talk to them and you'll find out, it's passion that sustains them through the years.
But that does not mean that they disregard the commercial realities. If your clients want angsty fine art photos, that's one thing. But if that's not what your market wants, then your passion may well be misplaced.
The passion that is needed is the desire to make the client happy and improve his life in some way. That's different from the passion to create something you like, or something artistic.