People do stupid things. Especially kids.
Nowadays we just hear about it more often, and the things that happen are often incidents which couldn't have happened in the past (like lasers). So there is a novelty to it.
Remember those tales of the 50s and Teddy Boy gangs? Knives, bike chains and gang fights? Same with skinheads in the 60s/70s, or the street gangs of youths of the 1920s/1930s. There was no Internet or multi-channel TV
service to report it then.
What we see nowadays is just a modern version of the kind of behaviour that has always existed. Except some politicians use it as a straw man issue and claim it's both new and increasing, in order to whip up hysteria and votes. It's also good material for news services looking to fill their content out.
Lead me not into temptation, I can find my own way there...