That's a situation that you should expect to end up in if you join an early stage startup - most people at the series A/B aren't there at the IPO. You can make

That's a situation that you should expect to end up in if you join an early stage startup - most people at the series A/B aren't there at the IPO. You can make the choice as to whether to take the risk, or you can seek out a company that will provide you the upfront cash needed to exercise in exchange for a significant portion of the upside if a liquidity event happens.