Since Paul Graham was talking about the best not the average undergrad, he ought to consider the competing options for them.
He fairly judges grad schools as pretty attractive.
He is wrong about elite employers though. Here is a stat nugget from one that is recent:
“The firm currently has around a 200-to-1 application-to-offer ratio in our region. And roughly 90 percent accept offers to work at the firm. We think this is an important “health indicator” of our talent value proposition. This percentage does not change much year to year. What varies over time is where the competition has been.”
Starting a high-beta-but-learning-rich startup vs the nice round experience of a globally recognizable brand is not obviously in favor of actually starting.