HD-DVD = Microsoft competed with Sony for who could set the standard for the marketplace. Sony won with blu-rays.
Zip drive = anyone remember these?
minidiscs like Ken said. They seem to have had their use for a brief time, but the dawn of digital devices with internal memory were a way better choice.
Sega CD = it was revolutionary at the time because of being able to see video on your video game console was innovative. But it quickly became outdated because of poor video picture quality that was instantly phased out once better game consoles came along, and once the gimmick wore off that most games with video (or FMV) were barely playable.
I guess 3DO, besides absurd price in 1993, was also similar. Although even more interesting. They had planned to make every video game console a standard thing, kind of like with TVs. You can buy any TV and use it for the same purpose. Well obviously that didn't work.
3D and Virtual Reality are also things that seem to come into fashion as hip new cutting edge tech, but they are always just a gimmick.
The guy LGR on youtube has a lot of old failed tech on his channel. It's late and nothing comes to mind now but there was some hilariously stupid ones.