If you have a family, your costs are astronomical. Mortgage, daycare, multiple cars, school-related fees.
If you're single, you're dealing both with the gender-imbalanced dating market (the imbalance hurting both men and women), as well as the difficulty of saving for a SV mortgage. If you plan ahead of time, coming into SV, that you're going to leave SV eventually because of the high cost of living, then that future move is going to come at the cost of most of the professional and personal networking that you built up and will have to say goodbye to, and build all over again after you move.
Sure, SV is the mecca for professional networking and VC funding, but a) you don't need to be in SV to be successful (counter-examples abound) and b) is it really worth it?
The death of cheap eats in the Bay Area is just a symptom. You're either making enough money not to care, or you're wondering anyway whether it's worth it to live there.