That is the entire point of an index. If you think that cryptocurrency is likely to do well in the future, but you don't know which ones will survive, if you bu

That is the entire point of an index. If you think that cryptocurrency is likely to do well in the future, but you don't know which ones will survive, if you buy them all (market-cap weighted), you'll get an average cryptocurrency return. For the S&P, the index has performed well for decades, but many of the individual components have not. Roughly half of the constituents have been replaced since 1999: http://www.businessinsider.com/sp-500-index-constituent-turnover-2015-6 http://www.businessinsider.com/sp-500-index-constituent-turn... And 87% of the companies present at the inception of the index have left the index: https://www.fool.com/investing/general/2015/11/22/3-things-you-never-knew-about-sp-500.aspx https://www.fool.com/investing/general/2015/11/22/3-things-y... If you believe that crypto is doomed, buying an index is a bad idea. If you believe that the future is bright, buying an index might be interesting. As you cautioned, implicitly, though, unlike companies, a held coin doesn't actually make nor sell anything. It's more like buying a forex index than a stock market index.