Companies like Monster and Redbull are marketing companies that happen to sell energy drinks.

That is almost certainly not a meaningless demographic they pulled out of thin air. It might not be meaningful to you as a demographic. It might even be offensive to you as a demographic.

But, to the marketing company, that is a concrete “group of humans” that respond well to their product and advertising. It informs how they develop their ads, how they target them, which geographic markets they push hard in, what events they sponsor, etc.

When they define that demographic as the people they’re targeting, and allocate their capital towards targeting them, they see the highest returns they’ve been able to find so far.

The world is so much more beautiful when you don't know how that works.