Ethereum reached an all-time high above $400 Monday, continuing a surge in cryptocurrencies in 2017. The cryptocurrency jumped as high as $415.31 a piece, up about 5,107% since the start of the year. At the same time, bitcoin reached another all-time high over $3,000 over the weekend, over 210% year-to-date. The price of both cryptocurrencies had retreated by early …