If my high school was any indication, I guarantee you that 99% of those students "marching" didn't give a damn or even have any idea why they were protesting. Something like this happened when I was in 11th grade: the principal was getting sacked after that year and a group of students decided they wanted to do some kind of protest in the parking lot against it. It ended up becoming some kind of party/rave with people showing up because it was an excuse to not get caught ditching class (safety in numbers logic, I guess) and most of them had no idea what the whole thing was actually for. Just a bunch of sheeple doing what the rest of the kids were doing.
It wasn't even clear at the time why the principal was getting fired. Turned out she illegally changed some dumbass emo kid's grades because he threatened to kill himself if he didn't pass his classes (which he just sat and did nothing in, not bothering to do any work).