Warning, this list is the saddest thing you will read all day. The only good thing about this list? At least you are not on it. Wouldn't it be great to have a crystal ball? Some way to see into the future and learn if you just made a genius decision or a regrettable mistake? The folks on this list sure could have used that. The tech industry is littered with stories of people making choices that would cost them hundreds of millions or even billions of dollars.