All you needed to know about student activist David Hogg’s speech at the "March for Our Lives" in Washington, D.C., was that he affixed a price tag on the microphone to symbolize how much National Rifle Association money Sen. Marco Rubio took for the lives of students in Florida. The stunt wasn’t out of place. Indeed, it perfectly encapsulated the braying spirit of the student gun-control advocacy in the wake of the Parkland, Florida, school shooting.