I'm not going to sell this as a great idea or anything, but just some numbers because I calculated them for myself..
Buy $500 worth of bitcoin in april 2010 - worth roughly $360 million
As a comparable - $500 worth of uber in 2009, which you cant buy because of SEC regulations, restrictions, you not being a cool angel, not being in SV etc.:
Buys you .25% of their Seed round which was probably worth 20% (industry standard?): .0025.2$70B = $35 Million. Thats just 1/10th and excludes any dilution, of which there must have been a lot. And you still cant liquidate this at all. The company may not even be worth what it says its worth.
Ethereum: In the initial sale, 2000 ETH were worth 1 BTC which was worth roughly $600 at the time. 1 Eth is now worth ~$200. $200*2000 = $400k.
For a comp, lets go with Robinhood. Its difficult to find "famous" startups that are only 2 years old. Robinhood had a $3M seed in dec 2013. $500 out of a 20% seed buys you .0033% of the company. Which you cant get because you cant invest etc.
Robinhood has recently raised a C at a $1.3B valuation. Your stake is now worth $43k. Pre-dilution. And you cant sell for another 10 years.
I'm not going to do this for every coin, but im pretty sure that we could find a really hot startup that is easily beaten by litecoin, dogecoin, ripple etc.
I'm going to put $500 worth of BTC into every ICO from now on. If the outliers pay for the duds in startups, theres no reason that it shouldnt be working in crypto.