> “So if Twitter is worth $25 billion and its size is X,” thinks the VC to himself smugly, “this other startup must be worth $250 million because its size is 0.

> “So if Twitter is worth $25 billion and its size is X,” thinks the VC to himself smugly, “this other startup must be worth $250 million because its size is 0.01X.” Isn't the main justification for these valuations growth and potential maximum size? Surely an investor can't extrapolate a $250MM valuation based on relative size with a straight face, especially as their metrics will also look quite different.