It may seem like a conspiracy by the gas companies but I doubt it. There is no shortage of gasoline today. The main reason prices go up and down a lot is because the value of the dollar fluctuates so much.
People love to target big oil as the enemy. Yes they make a lot of money because we buy a lot of gas. They must make a good profit to be able to finance the exploration for more oil which we demand at a cheap price , while we tell them where they can not explore. The fact is that the profit as a percent of sales for the oil industry is actually lower than it is for many industries.