I was kind of an introvert in high school and I know it is cliché, but I moved to SF and found myself. Everyone should live in a place like SF for a year when they are young. Maybe "your" SF is New York or maybe it is Singapore or maybe it is Vancouver or London or Berlin. The point is, if you are on the fence about the adventure, I recommend you take the leap.
Cons: Unhappy populous, rampant rule-breaking and crime, crumbling infrastructure