This will sound patronizing if you've actually lived here but... you do know that San Francisco is not "the valley", right? The "valley" is Santa Clara Valley , which is a full 45 miles away and a very diverse set of neighborhoods. "There are no slums. There are no marginal areas." I've lived in "the valley" my whole damn life. My family has ties going back to the gold rush days. I have no idea where it is that you l…
"The Valley" is more a metaphor than a specific geographic location. Yes, its origins and core are in Santa Clara County, but there's been a significant shift toward the urban mecca of San Francisco, and by broader definitions it can be said to stretch as much as 100 miles (O'Reilly & Associate's Sebastapol headquarters have been included in the term, though that's a bit of a stretch). As for slums and marginal areas…
Regarding affordable living, I think you'd be suprised what you can find. In just about every county there are affordable housing developments and less affluent areas. Those people taking your fast-food order for minimum wage and cleaning your house have to live somewhere.
Of course even entry level jobs in tech preclude you from the government assistance many poor people here rely on. But "I make too much money for affordable housing" is bit different thing to say than "SF has no place for you to fall ... There are no slums. There are no marginal areas."