Having moved to Austin in 1994 (when rent was only $250) to start my studies at UT, I discovered the town of Linklater's Slacker. I could bore you with tales of once-was Austin, like when SXSW wristbands were $35; every former Austinite has similar stories relative to the period of time in which they lived there.
Underlying all these stories that seemingly describe some mythical land of milk and honey is one common thread: opportunity. Austin allows you to be anyone you want to be and affords you the opportunity to do whatever makes your heart full. Austin allowed me to serendipitously become a very successful software engineer and I will never be able to answer the question whether it was me or my environment that played the larger role in making me who I am today.
I no longer live in Austin proper, rather the Texas Hill Country, just to the west. I am quite sure that from my vantage point, I can still see new Austinites like David experiencing the same wonderment I did almost thirty years ago.