"Uncertainty", also called "Knightian uncertainty", is like risk, but not quite the same. Risk is when you can calculate the probability of gains and losses, like when you play roulette or blackjack. Uncertainty is when you don't know the odds. Frank Knight observed that entrepreneurship involves a lot more uncertainty than risk. When you start a new business, you don't really know how to calculate the odds that your idea will succeed - whether personal computer users will embrace a graphical user interface, whether people will want to post their pictures on a social network, etc."
This is similar to a theme of my research that says that speculation is in part an attempt to deal with uncertainty. Knight argues that entrepreneurship is not about risk (as this can be quantified and insured or hedged away). As such, the wealth of the technology entrepreneurs is a return for taking a gamble when the odds are completely unknown. As Noah Smith says, people do not like uncertainty. They at least want to know the odds.
Smith argues that the return to uncertainty is overpriced. He cites the discussion by Felix Salmon and Gideon Lewis-Klaus' book No Exit. However, can this be the way to look at it? The risk or odds are unknown. If you want to think of it this way, there should be a balance of supply and demand and, with supply of potential entrepreneurs increasing, the price should fall. This is not the return that comes from success but the probability of being successful. The same amount of success could be spread over more entrepreneurs but it is not clear that the amount of success is fixed. In other places it is argued that the more the supply of entrepreneurs, the more the chances of new and successful ideas.