If one looks at the inputs into the cost-of-living issue, I suspect one would actually find that much of the pressure cooker atmosphere is the result of bad policy. There's no shortage of land, energy, labor, or even water* in Silicon Valley. But there's an enforced shortage of these things, and the resulting high prices create the "banishment effect" for these children.
* Since I'll take some flak for this, here's one supporting view: http://www.city-journal.org/2015/cjc0402vdh.html
Anything below a 3.9 and you were seen as not all that interested in academics.
To achieve this, you take probably 3-4 honors classes freshman year, along with the dreaded dead weight PE and a language if your school doesn't offer an AP language.
Then you transition to 2-3 AP classes as well as 2 honors classes (Precal and English) sophomore year, as well as secondary PE.
Junior year and senior year you take 5 or 6 APs.
Then, if the competition still has not been shaken, there is option of enrolling in supplementary colleges at the local JC after school or over summer (which, nicely, also are measured out of 5.0 on the HS transcript).
I enrolled in a mid tier private college instead of a UC due to fear of working harder than I did in high school.
I cannot believe how much free time there is. I'll probably transfer up soon. We'll see.
The kids I spoke of lived in shady canyon and had a ton of competition to get good enough grades to be in the advanced classes because if you weren't in the advanced classes you wouldn't get into the AP classes and have a higher GPA and get into the "good" college, get the good job, etc. This is from the perspective of seeing a good friend and her kids. It seemed immense pressure to me looking in but most of the kids got almost perfect SATs, were in multiple extracurriculars (soccer, track, putting on a community concert, etc.), acted in commercials, etc. I thought they were all insane personally. :-)