Eh. They can keep it. • Average engineering salary in sf: 116K / year [1] • Average rent for a one bedroom: $2,700 / month [2] After taxes you're coming in around 72k / year - 32k / year for rent You'll have roughly 40k to play with. That may sound like a lot but factor in food, health care, travel, energy, internet, phone, and numerous miscellaneous expenses and you'll be hard pressed to save anything over 10k a yea…
A good friend moved out to SF and loves it. He's mid twenties with no family, and living in sublets for 3 months at a time is fun for him. I probably would have dug that 20 years ago, but doing that now, with the prospect of moving to some lame suburb and commuting 2 hours when I start a family isn't so appealing to me.
In other words, most people do what works for them, today.