Because FTTP involves massive upfront costs with no hope of 10x or 100x returns. Say you sell fiber at $70/month. The operating profit margin of a company like Charter, which doesn't have a media-arm to rely on, is like 10-15%. So per year, each subscriber is worth $80-126. Over 10 years, discounted, that's under a grand. And to wire them up, you have to spend about that much if not more, up-front.