It's likely quite profitable, they don't buy bandwidth from Amazon, they get a few colo'd machines or dedicated servers in many DCs - you can get dedicated giga

It's likely quite profitable, they don't buy bandwidth from Amazon, they get a few colo'd machines or dedicated servers in many DCs - you can get dedicated gigabit lines in several DCs for a few hundred a month. Most subscribers only use the service occasionally and won't place that much load on it.