Randomness!
There are some super smart guys on this forum who think they can predict coins like LTC due to actual facts. It's almost hilarious if it wasn't so pathetic. The truth is 90% of big moves are irrational and based on intangible human moods and whims.
I've made more money than most simply sticking my finger in the air and testing the mood, often being contrarian rather than following the crowd. But seriously logic is the last thing you want to follow.
I think you are wrong a bit. Trading is not only the matter of luck but of skills as well. Yes, there are no guarantees. But there are some probabilities. For example, there is a very low probability that bitcoin will reach 2000$ tomorrow or fall to $700. And, similarly, if you see some coin was quite stable and than started growing+ there are people who believe it's good (on this forum) + the currency is at least a few months old - it is very likely to grow in price at least a bit more in the following days, so you can buy right now and wait for good time to sell it. Or you can just predict that the price will still be growing and will most likely reach some point in a couple of days.