[ghaff]

San Francisco is an extreme case. But somewhat similar dynamics apply to a number of US cities. Up through the early 90s or so, companies were far more likely to be moving out of the city rather than moving in. Boston/Cambridge had very little tech (and what they had was mostly consulting) at that time. Everything was out at Route 128, 495, or even southern New Hampshire.

Furthermore, the majority of the people I knew weren't particularly interested in living in the city. Some of that was because it would have required a longer commute. But, in general, there wasn't even a particular preference among recent grads for living in town. Some did, but it wasn't the norm or even especially common in my experience. This is partly because, by and large, US cities were not as pleasant places at that time and this in turn led to less investment in transit, etc.