I didn't say it's free of cost. My point is that a terabit of bandwidth delivered to consumers in a particular geographical area doesn't require a terabit of bandwidth from the center to that area, because much of the content can be cached.
So the 'terabit of network' the content provider needs to build need only span a few hundred feet within a single building.
I never said it did. You still have to build whatever you want. A terabit of edge network is a terabit of edge network that has to be physically built.
Not all networks are the same. Some have terabit backbones and gigabit edges, some have the reverse. We'd still call both of them, roughly, terabits of network, and you still have to build them. The one with the terabit core might actually be easier because you have less of the expensive really fast equipment.
In some ways it's less scary: no long inter-site fiber runs that I assume are an absolute nightmare, and no renting those same runs at exorbitant rates. All your hands-on work remains in the datacenter, which is set up to make it a breeze. In other ways it's more scary: you have to negotiate with a lot more counterparties and visit a lot more datacenters.
