This is cool and it's always smart to check past implementations like this. As long as you learn why the failed not that the idea is impossible. VR is a good ex

This is cool and it's always smart to check past implementations like this. As long as you learn why the failed not that the idea is impossible. VR is a good example; I didn't see any companies on that list but many gave up on VR because it was too early to be possible until a few years ago. Another good example is digital currency. Also; you can learn from a comp like Clinkle which should def be added to the list