Google Fiber has won a lot of customers in Kansas City, where it first offered fast Internet service, suggesting the initiative may be profitable, according to a recent survey. When Google started building Fiber in Kansas City in 2011, Wall Street considered the effort an experiment. Earlier this year, Google identified 34 cities for possible expansion. That prompted concern among some analysts and investors that the high initial cost of building a speedy Internet network would generate slim returns, or no returns at all. A lot depends on how many people sign up for the service, and the early signs are good, say Bernstein Research analysts Carlos Kirjner and Peter Paskhaver. Kirjner and Paskhaver hired market research firm Haynes and Co. to go door to door in Kansas City neighborhoods to ask residents whether they had Google Fiber.