I've been thinking about the feasibility an ETF for all coins and assets. If such a thing existed then you could have invested that $100 in lets say CRYPTO1000 on 1/1/2015 when the market cap was 5.5 billion USD and today it is 155 billion USD. That's a 28.2X gain so you'd have $2820.

You could also get lucky and put that $100 in ETH alone at the ICO and have made $220446