You're certainly correct about the opportunity cost of forgoing higher guaranteed comp at a BigCorp in return for a potentially higher reward, but I don't think that directly relates to the question of job security.
Now, maybe we are in a bubble and maybe we are not, but the tech sector has a history of very sharp ups and downs, and in the downs? my experience is that a lot of pretty good people end up un[der]employed.
The other interesting thing is that from what I've seen? Layoffs at big companies (and if the sector takes a dump, there will be layoffs) are generally more "fair" than interviews at the same places. By that, I mean that those people who are shy but good are often the last to get laid off, but beyond a certain level, when interviewing, the "shy" part hurts you more than the "good" part helps you.
I had to move to Ann Arbor to find my next job.
The thing about the daisy cutter that Patrick said is not a myth. If you're one of the people here that believes we're in a bubble, you should take it seriously. They didn't call 2002 "Nuclear Winter" for nothing.
I moved to NYC to get a semi-functional job market.
These days the possibility of highly correlated failure is a major component in my career decisions.