How is it the end user's fault that Comcast's network can't handle everyone using the service they paid for?
I understand that everyone does overselling because it's profitable, and makes sense, but don't expect the customer to not use what they are paying for because you have oversold your services.
No ISP on earth can "handle everyone using the service they paid for", the same way that the electricity grid can't handle everyone using their full 100 Amp supply.
Jeez, I'm really not a Comcast apologist, I'm not sure how we got here ;-)
But in reality you, and I and Patrick above, as probably power users of our internet service, benefit from this overselling. If an ISP actually had to provide the entire bandwidth cap to all their users the only way they'd be able to do this is by raising their prices considerably. Instead they stick a high cap up there to discourage people soaking all the bandwidth with torrents and try to provide the best level of service they can.
The other option is for Comcast to provide the service as advertised, at the current price, yielding a reduction in profit. No business wants to do that obviously, however since Comcast effectively has a monopoly in many markets, they can't (should be allowed to) abuse their market position.
I understand that everyone does overselling because it's profitable, and makes sense, but don't expect the customer to not use what they are paying for because you have oversold your services.