I built a competitor to Reddit and Digg (at the time) called RatherGather that had some differentiators that ended up not mattering to people. I wish I understo

I built a competitor to Reddit and Digg (at the time) called RatherGather that had some differentiators that ended up not mattering to people. I wish I understood Metcalfe's Law better at the time. I built a mobile game called Roaring Racers where you had to use your voice to make your car move (roar louder, go faster). I built a stickers app for iOS stickers launch that allowed you to import anything. This one wasn't a total dud, but the way Apple positioned the store, the traction wasn't at a scale that made it worth my time. And then of course there's the laundry list of companies that I've been employed by and built products for where months into it I discovered nobody in the company had really done any market testing, but they got clearance to build something for $XXX,XXX anyways. 9/10 startups fail, so just by nature of that fact, most of us spend our time working on building tech that never really "makes it". There have been great successes too, but you asked about the failures.