Founders like Mark Zuckerberg care deeply about dilution because they want to remain in complete control of the company for as long as possible. If you're like that, the percentage matters more than the absolute dollar value of your shares.<p>Investors also often care about having the power to dictate the terms of future rounds and/or acquisitions. Dilution reduces this power, and humans are known to sacrifice a lot of good things in order to obtain and maintain power. Feeling powerless is very different from being penniless. This might explain why so many people are obsessed with percentages even at the cost of dollar values.