One of mine: a few years ago I almost ported over (it was 99% done) an interesting piece of technology to mobile. Something fairly technical and low level. In the end I thought it wasn't possible to get it working, so called it a day.

Five months later some other guy ported the exact same thing, and made a million euros. It was something that basically marketed itself; something you upload to the App Store and it would've sold. So that money would've been mine.

And then I revisited my old code, and noticed I _could_ have gotten it working.

It happens. Ah well. I still made plenty from other apps.

Now I am looking foward to RChain https://www.rchain.coop