It is not the protestors that fire a shot, but, as the incidents I mentioned show, the shots often are fired upon those protesting. We are often led to believe that we should turn the other cheek, but eventually, we run out of cheeks to turn. MLK turned the other cheek, and wound up knocked on his ass by a bullet that ended his life. Sometimes peaceful means have proven ineffective. Many of today's protestors are looking at history. The peaceful protests had violence turned against them. so "Back in my day" would refer to demonstrators that were treated violently by the authorities. Remember Birmingham in 1963? peaceful protesters from 8 years old an up were sprayed with high power water cannons and had Police dogs released on them. And that was just for starters. As more people remember those incidents, the odds of violence come to the forefront increase. The French Revolution started with such violence, against the demonstrators and the authority figures to overthrow an uncaring, corrupt government. The US, likewise, started in such a manner.
The people evolved to try and demonstrate peacefully and all that got them was injuries, if lucky, and death. One reason why education has been stiffled about such demonstrations. Do not be surprised that violence may come from today's protestors. It appears that when our leadership does not fear for it's life, despotism comes to the fore.