50/80 Rule: Once you've used 50% of the available time, if you're not 80% done, you are behind.
Things That Cost More Than Space Exploration costsmorethanspace.tumblr.com
Optimism is believing you can discover currently unknown solutions to your problem without also discovering more currently unknown problems.
At $2B Oculus VR was only worth ~1/10th of what a chat app was worth to Facebook. I think these prices are worked out with a magic 8 ball.