There are lots of reasons for the increase, a few have already been touched on. One that hasn't been mentioned is the worldwide trend. Developing countries are using more.... much more than they used to. China and India, for example.
We haven't built a refinery in 30 plus years, so even if we could get all we want, cheap.... it still wouldn't make a difference unless our cars ran on crude.
Yes, the gas companies are public and the bottom line is make money for the investors.
These e-mails touting do not buy gas on such and such a day aren't realistic in any way, other than to make you think you stuck it to the man. Actually you didn't, cause you're gonna fill up tomorrow anyways. But if it makes you feel good, go for it.
BTW- we've had a tremendous run of cheap gas for many decades. It looks like that may be over, or getting there. We're gonna have to pay what the rest of the world pays eventually, so buckle up! Europe's been paying twice what we do for years.