There seems to be a question that's in vogue on the interviewing trail these days: "What are you passionate about?" It's a good question, especially for startup hires. You're going to work your tail off, so having the proper motivation is critical... and "I'm in it for the money" isn't going to cut it.
The preferred answer seems to be "I'm passionate about..." and then fill in the particular application or service the hiring company is built around. I think this is misguided. A better answer would be "I'm passionate about building a great business."
Why? Because most startup's don't succeed at whatever they started out doing. Sometimes, what you thought was a product is really more of a feature (see this post from Mark Cuban for example). Often times, you're iterating toward the product or service that's going to resonate with the market. So what happens when the thing you've identified as "your passion" isn't accepted in the market? Some would argue in favor of staying the course, figuring that the market will eventually understand the value of what you have to offer. Maybe. But more often than not, these are the people who believe in the phrase, "we didn't lose, we were just behind when time ran out."
The successful entrepreneurs are the ones that set aside their own feelings and read the market acceptance information for what it is. They adapt their product vision to address the opportunities as presented by the market. Are they passionate? Absolutely. Are they obstinate? Not so much.