I'm not getting it because the reasoning is not sound. Your reasoning is basically "the numbers are BIG! so a factor of 2x doesn't matter". If you can get your lottery tickets for half price, you can buy twice as many lottery tickets, and double your chances. Equivalently, getting 1% of Google or 5% of Google is a 5x difference, which is huge. That could easily mean the difference between a net profit or net loss for an investor over all his investments.
If you really believe that the terms don't matter, then I'm sure lots of YC startups are happy to take money from you at terms that are 5x better than what YC offers.