I was looking at the price history of the top 50 coins and they all seem to have very similar price charts. They all seem to have spiked up the first half of this year even if they have been around for several years. My question is what caused all these altcoins to surge up in value so much?
Because in first half of 2017, BTC has been growth strong and stable, then ETH and XRP join this trend and prove 2017 is year of cryptocurrency with growth ratio change 1000-4000% just in short time. After that happens, all market are increasing and just need buying, you can become rich man 
. But this trend ended in June and make bearish trend until today