What, exactly, does Comcast have a monopoly on? Basic internet access might be considered a necessary utility, but an unlimited 15MB line is certainly not.
So why stop the service, charge more for more data use. Or perhaps throttle your speeds. I think he means monopoly in the terms of disallowing service, I guess he should be ok if they charge him more money for more data usage. Either way I believe there is a monopoly where as locations and service providers are concerned and many a times caps such as 250GB are extremely arbitrary. I mean really whats the technical reasoning for a uniform cap of 250GB whether you are in downtown NY of Seattle? Also I would read this... Extremely thought provoking...
http://news.ycombinator.com/item?id=2709834
It's cheaper for Comcast to cut off a few "problem" customers than it is for them to actually invest their record profits in upgrading residential infrastructure.
Just because something is not a fundamental human right does not mean that it's not possible to have a monopoly over it. Monopolies are a problem, regardless of what they're providing.
5mbps? You're lucky. I live in a densely populated area of another major city in the US, and I can't get anything faster than 3mbps from anyone, no matter how much I'm willing to pay...