[primedteam]

I would work out the difference between the salary at say Google vs what you took during your tenure at the startup then double it because of lack of upside.

Aside: If the co-founder is an HN reader, then they probably know the throwaway account is you. That is going to skew this negotiation.

[danshapiro]

I believe this is a sunk cost fallacy. The present value of the shares not based on the OP's previous foregone financial opportunities.

[owens99]

Agree with this. What the OP could have made at Google is not his CEOs problem.

[johnchristopher]

Might also be the other party testing the waters.

edit: of course, parent's comment regarding the other party is still sound and valid :).

[throwaway21122]

lol, it is.

for the record, i'd probably do it if i was offered $500k.

[fzzzy]

Then ask for 500k.