I think a key difference between someone like perhaps yourself, and a lot of people here, is that they're thinking less about the number valuation of a company (formulas that we've made up), and more about whether we like the company and believe that it's going to grow in prominence in society. I think if you thought like this about Amazon before (and less about what you thought its number valuation was), you might've been closer to anticipating how much it's grown.
Obviously this isn't bulletproof and we can't fully anticipate what's going to happen, but to me, my belief in a company is about the best option I've got.
Also, I think focusing on the number valuation of companies is a great way to feel like you are in control, and can predict how things should and will be, and then get frustrated when it often just doesn't work out that way.
