If startups are negative expected value, the KC is not useful: it presumes bets are positive expected value and the question is what fraction to bet at any time to avoid ruin.

On the contrary, in some sense, that's when the KC is most useful. The correct amount of money to gamble on losing propositions is 0!

My estimation of startups in general is that startups are a good way for exceptional individuals to capture much of the value they create. The problem is that it's difficult to tell who is exceptional beforehand, especially if one can only measure sparkle and not grit, and also especially if one has not determined their own level yet.

In that vein, I am cautious about finding cofounders in ways like this.