I was talking with a friend last night, when I found out she got the exact same score I did on the SATs: 1590. She is younger than me, working menial jobs in the immediate post-college funk, and went to a no-name liberal arts college instead of even applying for big names like MIT or CMU.
And it occurred to me that I know 3 broad user-populations among my friends: 1570s, 1590s, and 1600s (yes, I categorize my friends by SAT score and have a sample size of at 3-4 in each; I told you not to take this post too seriously). The 1600s are grinds, but smart grinds. Think of Hermione Granger from Harry Potter. Google is absolutely loaded with these people - on my team alone are two people who graduated college at age 20 and numerous Stanford/UIUC Ph.Ds, and I've worked with IMO gold medalists, etc. My friend's boyfriend (also a Googler) scored a 1600 on his SATs.
The 1570s usually end up being reasonably happy in high-level professional jobs. They get a nice six-figure income, and then they concentrate on other things like their family. And they don't worry about it too much; they're doing just fine.
It's the 1590s that end up being crazily insecure. I know several of them, besides myself and her. And while the more well-adjusted of us hide it pretty well, it seems like there's always this desire to prove ourselves, which seems to come out in the form of occasionally odd behavior and attempts to push the envelope. My friend is always asking me why she's crazy - she's not really crazy, she just tends to make decisions that have an odd form of internal logic that makes sense to her but are probably not what other people would've done. Sometimes they work out, and people herald her as a genius (which isn't really helping); other times they don't, and they despise her as a crazy bitch.
The most famous 1590 was Bill Gates, and you can definitely see this pattern in his business decisions. Not all of us have wealthy, socially-connected parents and lots of money to fall back on.
You're right that this sort of behavior is a sickness, of sorts. And the cure is to realize that it just doesn't matter all that much. Whether you got a 1600 or a 1590 or a 1570, what matters is the people around you and the task at hand. And being smart can help you with those tasks and make it so that other smart people want to be around you, but it doesn't define you. It's a number that one test assigned to you back in your formative years.
As for why Google instead of a startup - it is much easier to realize that these issues don't matter when everybody around you has them too. It's like they fade into the background. Everybody has their 1600 SAT or Ivy League degree or IMO gold medal or past startup or open-source project, and so you can't measure yourself by your accomplishments. And so, if you're smart, you start measuring yourself by whether you're pleasant to be around, or whether you make the lives of the people around you easier, or whether you can understand & make users happy. Eventually this becomes a habit, and - I'm hoping - that can be taken to experiences throughout the rest of your life.
I speak from experience when I say that startups - unless you really luck out and find the right startup - generally don't offer this. It's far easier to lose yourself in the desire to prove yourself when the rest of the world doesn't give a damn about you.