Is it a common experience that, as a single person in SF, you'd make $100K and end the year without any money saved? I'm not asking with any judgment or critique implied. I'm genuinely curious if that's normal in SF.
But it's also the lifestyle that forces this. I was continually perplexed at how all of my colleagues seemed to be able to afford to go to all these conferences (not always on company dime), buy the most expensive coffee, upgrade their bleeding-edge laptop the moment Apple puts out a new one, and so on. I figured out later that they just weren't saving or investing any money, and often were even accumulating debt despite their high salaries.
The culture of always being at work (or at least seeming to be) is a factor too. More and more of your meals are eaten outside the home. A lot of people use cleaning services.
Some people feel they need to do all this to keep up. I'm not sure they're wrong. When I pulled out a three-year-old iPhone, people gawped at it, like it was the Ark of the Covenant or something. I lived in a district which was not the Mission or SOMA and people acted like I lived off the edge of the world.