The minimum wage protest

Lately protests of sorts have started to occur in the fast food industry. And it is about how much they are getting paid now and what the future pay should be. And the protests are getting louder. So what is the issue here? It is that the workers say that they are getting the minimum wage of USD 7.25 or so (coming out to approximately USD 15,000 or so based on forty hours) to at least USD 15.00 hours or more than double of what they are getting (which comes to USD 30,000 based on the same hours). Another protest is also going on with Wal-Mart® employees who are saying that they want at least the wages should be minimum USD 25K. Although I sympathize with their plight but to demand double of what they are making is particularly absurd to me. And since I am not a conservative person who may be against this raise, let us analyze this issue before we get carried away with emotions. It is nice to protest for what you believe but is it really your right to demand such huge increase where the margins are thin. Although fast food companies are making huge protests but they have to earn money for their investors and also hire more people. When I was applying for jobs even with my MBA degree I was being offered jobs with USD 15.00 and that was a stretch too and generous on the part of the employers. So how can the protestors expect to be paid so much so fast?