Ethereum is less volatile than other cryptocurrencies. A lot of ICO projects create ERC20 tokens and use ETH blockchain for smart-contracts. While the situation will be the same, price will keep stable. But when some another blockchain networks will be using for ICO, ETH price can quickly drop!
neo, nem, waves platforms are used on icos and the price of eth is still increasing up.
ethereum is less volatile than new tokens, if you want to invest and expect high returns, better invest on newer coins