With the United States and Europe leading the way, the broadly defined "gaming video content" industry is now worth a reported $3.8 billion. In its simplest form, "gaming video content" can be loosely defined as video content centered around video games. According to Quartz, this includes walkthrough videos (think PewDieDie), reviews, eSports, livestreams, and official game trailers. So, yes — billions of dollars are accumulating within an industry based largely on watching other people play video games. In fact, the journey to $3.8 billion is the result of a steady growth that's predicted to continue for years to come:

Quartz

With an estimated 500 million people currently engaging with this content, the industry is drawing comparisons to other highly profitable acts of enjoying life's momentum from the sidelines — i.e. traditional sports.  Thankfully, this is a spectator sport which involves practically zero physical interaction with people — significantly reducing the risk of receiving a concussion from a fly ball or a mustard stain on your crisp white tee from a nearby hot dog enthusiast.

To place all of this firmly into perspective, the aforementioned PewDieDie — a.k.a. Felix Kjellberg — made a quite manageable $7 million last year alone. Who watches the watchers? I'm not sure, but that's probably the next billion-dollar industry.