They're living in their parents garage. With the single biggest cost of living(housing) removed, I'm curious how they can't afford life at 80k/yr. Besides for housing, cost of living does not need to be particularly higher in SV than elsewhere. Either that, or the parents are charging them market rate to live in the garage, which is probably illegal anyway...
How do you figure that "besides for housing, cost of living does not need to be particularly higher in SV than elsewhere"? While housing is undeniably the most wildly out-of-control expense in Silicon Valley, the rest of the essentials of life ain't cheap either.
Rent makes up between 1/2 and 2/3 of my monthly spending. Most "essentials" are actually pretty cheap in SV (gas maybe being the exception). Unless you have kids and need to pay for childcare; and that's also a function of the high housing prices because the workers there need to pay rent also.