My wife is a fitness trainer, so I get to see both the good and bad of the fitness industry.
Current wisdom is that most people don't drink enough, the current goal says shoot for 1 gallon a day, so people lug the bottle around to help track/reach the target. Unless it's summer a gallon feels like a lot. I have tried to hydrate better with a glass of water at bfast, lunch, dinner, bedtime...
Now the humor, anything invented for fitness that looks cool, but causes no pain will be a big hit.
expensive earpods, sunglasses, gloves, tape, water bottle, hr monitor, tights & legwarmers, gels all look great and don't hurt, 10 x 400m, extra sets of hamstring curls to exhaustion, etc cause pain, so you won't see these much.