Regarding your point (1), there's more to it than just the dollar amounts now and later. If we believe the over-leveraged founder story where that founder has mortgaged their home and maxed out their credit cards, being able to sell that equity at series A for $500k could mean the founder is able to pay those debts, and doesn't end up losing their home and being hounded by creditors. (Even if it doesn't get that bad, having that debt over your head is stressful, and running a small startup is already stressful enough.)
If we also believe that founders are important to a company's success as it grows from a small startup into something more mature, I'm pretty sure that unfortunate financial (and housing) situation would drastically reduce the chances that the company would make it to that $250M exit later.
So taking that $500k may increase the chances that the startup later gets sold for $250M, rather than, say, $50M... or just failing entirely, returning whatever small amount of money is left to investors.
If we also believe that founders are important to a company's success as it grows from a small startup into something more mature, I'm pretty sure that unfortunate financial (and housing) situation would drastically reduce the chances that the company would make it to that $250M exit later.
So taking that $500k may increase the chances that the startup later gets sold for $250M, rather than, say, $50M... or just failing entirely, returning whatever small amount of money is left to investors.