Do coders (like at Twitter) typically make over $200K/yr? Or do they just eat ramen every day?
In some cases the importance of saving is realized, but offset by the certainty that they're going to cash out huge Any Day Now(tm).
I know one guy (not at Twitter) making around $180k. But his real brilliance was getting in around 2007 and staying in the same place. Right now he's paying around $1500/month for a really nice one bedroom on Valencia.
It's great that we have laws to protect him from predatory rent increases.
If you choose to go for high-end dining for every meal, you won't be saving very much, but $4k/month is hardy ramen.
Not every restaurant in SF is the French Laundry either.
At $70k a year, you should take home roughly $70k / 12 * 0.65 = $3.8k each month.
At $120k a year (rough estimate for a Facebook engineer, so correct me if this part is unrealistic), you should take home roughly $120k / 12 * 0.65 = $6.5k each month. If you're paying $3k each month on rent (which is quite generous if you're living by yourself), that leaves you with $3.5k each month.
That means that your $70k job only leaves you $300 a month for rent, in order to have the same amount of money left over. That's really pushing it, considering it's only half of the median USA apartment rental, and considering I paid $400 a month for a modest apartment 4 years ago in Springfield, MO, which as I understand it is in one of the cheapest areas in the country.
Obviously there are other effects here that I'm missing. My 65% take home portion could be completely wrong. Food prices are almost surely higher in SF (of course, most startups and tech companies provide some free meals).
Having lots of space is obviously a major difference, but is very subjective. Many people who live in a city probably wouldn't want to maintain a yard or a larger house or need to drive everywhere. I definitely prefer the space.