But looking back from my startup after my first job, I was relatively clueless in my first job.
And looking back from my big-company job after my startup, I was relatively clueless in my startup.
I don't think this ever ends. Rather, you just become relatively less clueless compared to all the other nincompoops founding startups. Repeat often enough and maybe you can convince someone to give you lots of money.
A great point he makes is about friends and family (especially those not in silicon valley)--it's hard for them to understand why you would give up a stable job for uncertainty.