Turning 30 doesn't mean you're getting old; it just means you can throw a massive party in style that you couldn't have afforded at 21.
On Polk Street, no one's on the front lines of a subculture war. Polk Street has no "code," dress or otherwise. There is no one way to act, no one bar to crowd, no one scene to be seen at. No one San Francisco subculture dominates.