One trouble with fiber is that most people (who have cable) think the cable service they have is "good enough" in terms of performance, but they'd rather pay less for it. In fact, fiber is not that much better than cable, particularly when you factor in that TCP can't move a gigabit per second across the public internet anyway. And particularly when you consider that DOCSIS 3.1 is pretty fast and that cablelabs is working on filling in the gaps such as Full Duplex transmission.

In much of Telco land, however, the problem is that fiber already has competition in the way that your phone company sees it. In my area, a double play costs about $90 a month for 2 Mbps internet. Google Fiber costs less than that, maybe people in my area "should" pay a little more because it costs more to provide, but I can't see it going much past $110 a month (what cable internet would cost for 25x better performance if they ever build out in my valley.) It's not that a fiber service could not be profitable, but it is not a rational decision for a company that can make huge profits by doing nothing.

Another problem is that there is always some new technology that is going to "solve" the problem in the sweet by-in-by so that communities don't show the moral fibre to do the right thing. Google's Willy Wonka approach to fiber optics was one of the first of these, but next it is baloons, then it is WiMax, then it is drones, then it is 4G, then it is 5G, then it is large satellite constellations (if those get built, Elon Musk won't have to bother sending astronauts to the space stations and can head straight for Mars or the Moon because the space station gets shredded by space junk.)