Entrepreneurs have been described as missionaries in search of a cause. In a way, this fits, because the basic fire in the belly seems to be a common characteristic of most entrepreneurs I've met. Curious, persistent and innovative people possess the requisite resiliency for the speed bumps and occasional setbacks in the life of any business owner.
The entrepreneurial personality also seems invigorated by risk, a quality that, if not checked, could be the entrepreneur's downfall. Clearly, if you can't handle risk, you shouldn't start a business. However, "driving too close to the edge" or investing too much in an untested product or strategy can be the beginning of the end of your business.