I think "greed and stupidity" is taking it a bit far, but most people are not willing to spend an extra $200 to patronize an airline that doesn't act like this. United's stock went down but most people are not going to fly out of a different airport in order to patronize a different airline.
And before we call air travel expensive let's look at what it actually is. We've only been flying at all for about a century (much less of that time commercially) and it's already safer than driving to the airport. You can get from San Francisco to LA for less than $100 in an hour. Across the country (NYC to LA) for less than $400 in the amount of time it takes you to watch two movies and eat a meal. This is with something approaching $300-350k worth of annual payroll in the cockpit, flying a machine where the engines have to be literally broken down into their component pieces and rebuilt on a regular schedule. The overhead is obscene, the skills required to do the job are expensive, and they'll move you and a friend from one end of the country to the other for less than most people here would spend on a laptop.
The fact that a $20 difference in fare will make you choose one airline over the other is what drives all airlines to this point.