Earlier quoted context omitted.
Be careful to examine what's actually in the fund as your underlying. This isn't like buying the S&P500 where the sector exposure is well defined. One "startup index fund" can perform very disparately from another "startup index fund". edit: If there's data that shows the performance of a basket of random 100 company samples being equivalent to any number of other random 100 company samples, then I am happy to admit…
Yep -- I understand what I'm buying (well, not buying yet...). Something like this would be a great for a Taleb-esque 90/10 barbell I think -- 90% in target-date vanguard funds and 10% in startup investments by proxy.
I think your plan (substitution index funds for cash) is already a lot better than what Taleb suggested.