EDM is blowing up, it's the cool thing to listen to these days and festivals are the cool places to be. Kids initially get into Kaskade and Skrillex, then when they really dig into the other genres of EDM they discover the great old school EDM artists like Carl Cox and Hawtin. This probably happens when they start to wander around a festival like EDC, then stumble upon something mind blowing like Carl Cox. They do a little research, tell their friends, then they're full blown tech house fans.
I could be totally off about this, just my interpretation.