That is the entrepreneur's number one skill. His ability to take risk. And like all skills, he gets better at it over time.
Looking back, over the two years I have been on my own business-wise, I have become used to the life of uncertainty that comes with entrepreneurship. I am only sure of the money I have in my hands, I don't know where the next one will come from. In the beginning that was pressure in itself. It was like learning to swim, your first attempts will almost drown you before you finally start floating in the water rather than fighting with the water.
Gradually, you begin to feel comfortable with risks and seek more uncertainties. You rely on previous experience, book knowledge and opportunities you see around to make plans/decisions. And finally, you loathe anything that ties you down, that limits your options -- ultimately, waving bye to the employee world.
In this last two years, I have made money from every idea that popped into my head that I pursued -- from online training to selling books online to selling iTunes card to academic research to programming to teaching Excel. Though I have stopped a lot of them but they have embedded in me the ability to turn ideas and skills into money. They give me a sort of a safety net as I take on more risky ideas -- if they fail I can also go back to what I have done in the past that worked.
And I see this same skill in other entrepreneurs. They take more risks that non-entrepreneurs. In fact, it is their most obvious skill.