It's expected and actually easier for an Altcoins to grow 1000% than for already established ones like Bitcoin, Ethereum, Dash, Litecoin etc to grow with such an insane percentage in a bull market. But there are some downsides to investing in Altcoins too, it can dump by 1000% in a jiffy. The rule now is investing in good Altcoins with great community, reputable developers as well as good use cases. By so doing the risk of investing in Altcoins can be reduced to the minimum level. Cheers mate