Assuming I'm doing as well as he is (which I doubt) and that an exiting startup gets 10x the input, the formula suggests 25% or so.
This seems high. Also, startups are not independent bets. Who knows?
I've done 34-ish investments. One small exit. Two are doing very well. Two or three dead companies (sometimes, it is hard to tell.)
I guess that makes me a junior associate at best.
So that makes me subordinate to people who do these things; they are therefore my senior.
upshot: if he does well, in a couple years his typical investment size will be $20-$50K. Investment size is a proportion of bank.
Reading it inspired this: http://joshua.schachter.org/2008/09/amateur-economist.html
Curiously, I was a quant before I did delicious.