Startup products initially appeal to innovators, people who like to be the first to try the newest thing. They seldom spend a lot of money, but they're super important because they curate new ideas for everyone else who follows.
Then come the visionaries. These people are the trailblazers who are living in the future, and they see an opportunity for a new product to solve a burning problem that's blocking that better future. They're willing to take a leap of faith on a proof of concept.
Then come the pragmatists. No matter how well the product serves their needs, they need social proof to buy it. They're more motivated by not getting fired than by living in the future. They start using a product when they feel left out because all their other friends are starting to use it.
Jeffrey Moore shows that a startup needs to dominate a niche of passionate, visionary early adopters, but then expand from that position of strength, to early niches of pragmatist.