Google and Facebook are large and rich enough to replace the ISPs if they felt they needed to. They've both dabbled in this area and would surely turn it into a

Google and Facebook are large and rich enough to replace the ISPs if they felt they needed to. They've both dabbled in this area and would surely turn it into a serious effort if their core business was threatened. They just haven't done it because it's still cheaper (for them) to let the existing ISPs do it. Comcast/Verizon/etc don't want to pick a fight with Google or Facebook. They want to pick fights they can easily win and gain extra money from: companies too small to pose a threat.