can someone explain "reaction videos" to me?

[ΛΟΓΟΣ]

interesting question, its for the same reason that some people dont turn off the tv at night to sleep

Spoiler

afraid of being alone

tbh i used to ask the same, and i think you can apply this to many things
why watch something if you can do it? considering that something to do isnt out of reach
why watch someone play something if you can yourself play the game, why not try? 
why watch someone watch something if you yourself can do so? why not try?
considering the popularity of streamers, which is more recent and most of the times, devoid of content compared to what digital content used to be not so long, id say its more of a loneliness issue, which is brutal in modern digital age