3D movies, I remember everyone being so excited for shit like Avatar because it was a 3D movie without the dumb red and blue lenses. Then it turned out to just give you vertigo.
Or even 4K TV. Like it looks marginally better if your face is jammed into the screen, but all it really does is suck up way more bandwidth and cost $400 more.
I realize it was a slightly different time when everyone was just a little less overstimulated and deadened to constant emotional manipulation, but it's still incredible how effect a marketing campaign that was. Like it felt like everyone I knew started talking about it overnight.