Reason behind this very simple.The bigger youtuber's motivate them[I mean both directly/indirectly].So the kids feels a weird type of interest on them.So they try to do something different.They starts to record their self and tries what the audience would like.I support this will-power.But youtube isn't the only platform.You can be doctor or something else you can change the world by inventing new things.So guys in basic level don't take youtube as career.