I'm in Seattle so the situation is a bit better than the valley. But here's a breakdown:
L6 at Amazon, single, no kids:
~$400K TC
$33,333 per month gross
About $100K in federal tax, no state income tax in WA.
$8333 per month
Healthcare: $34 a month for an HSA plan.
$3,650 over the course of the year goes into the HSA, including the employer portion. That ends up being about $205 out of my pocket. This is a bit complicated if you're not American and familiar with the different account types but it's basically money you're saving that's not taxed, but you can only use it for healthcare expenses.
$3000 max out of pocket per year for medical expenses. For all intents and purposes you can assume that's the most I'll ever pay. Out of network stuff makes it more complicated, but my network has essentially everyone.
$250 a month, but you can use the HSA funds from above, so net $0.
Rent: In the Seattle area a newish one bedroom that's about 50-60 m^2 will run you say, $2200 a month. You can go cheaper or more expensive, but that will get you something that's plenty nice. Commute is extremely dependent on exact location, but if you're in the city, the majority of it has a commute time of less than an hour.
$33,333
-$8333
-$34
-$205
-$2200
=
$22,561 income remaining.
I think you'd be able to survive :)
Obviously doesn't account for internet, a phone, a car, utilities or anything else, but that's maybe another $2K a month on the high end.