Thinking about it, people move into something new only if the old is not working for them any longer. If that's the case, then frustration is the driver of innovation to a much larger extent than the realization of opportunity. The interesting thing about this notion is that frustration is measurable, while opportunity is not.

You can ask people what they don't like about the world around them. Usually they won't give you accurate information, since they have no understanding of their own pain – but that still beat asking yourself what opportunities there are out in the world. Even when you find an opportunity, you'll have a hard time selling it to others if there is no pain associated with it; that's my summarizing of the Internet bubble: solutions to problems nobody had.