You could easily spend 10k on commuting. That's only about $40/day. Between fuel, maint, tolls, and maybe food, you can easily bust $40/day in the Bay Area. That's not even considering the _time_ spent commuting.
And the worst part is that it wouldn't have to be my fault at all, and it wouldn't even require somebody to do something extraordinarily reckless. Driving too fast through my neighborhood is typical, because it happens to offer the shortest path from A to B for many people, and the road is wide thanks to bike lanes that I have never seen bikes in (because: cars drive too fast). I'll cut myself off here before this becomes an overly long screed.