Who said anything about killing the company? If we break a contract, we pay for that mistake, unless we get away without anyone noticing (or have thousands of lawyers). We don't get to just lie to people and steal their money and then whine when somebody wants their money back (or fines are levied in response).

There were far more than 50 million wireless subscribers on AT&T during this period, myself being one of them. The damages to me were far greater than $2 during the period after this change occurred, not to mention the $350 I paid to get out of my renewed contract after realizing how useless my data plan was, in order to get my work done when I was on the move. Even if there were only 10 million customers on the unlimited plan and each customer was impacted in a manner that could be monetarily valued at $50 over a period of many years, that would amount to $500MM in damages.

The killing part comes next when this FCC decision holds up in a superior court, providing the common law grounds for a class-action lawsuit. That will be many hundreds of millions of dollars, and that's the real reason AT&T will appeal this.