Entrepreneur
I can see better ways of doing things; too stubborn to fit on other people's payrolls for long...
Grameen Bank; Virgin; Kiva
Number of iterations required to convert good ideas into successful ventures; dealing with people who can't / won't grasp the potential of Big Ideas.
Assuming others can see their vision clearly
Cross-skill the entrepreneurial team, for skills and accountability and backup. Don't abdicate the parts that make one uncomfortable. Find co-founders and clients with different skills, similar passions.
A lot! There is a substantial knowledge base now, and sucking it in can really shorten the learning curve. School of Hard Knocks is a painful, and stupid, way of learning, so make sure it is supplemented with the best ENTR Ed. you can get!