I turned down a job at Apple in 2007, just before the iPhone release. I was offered 1500 shares of stock, which has since split 7 times. I turned down $1.8M that day, in addition to the increase in salary for making the jump. Plus, I would have received new stock grants each year after that. I'm not even an engineer, but a business guy.
All the focus on salary is really noise. The salary is just to cover your living expenses. Hopefully your stock grants hit and you make your money that way. Maybe, maybe not. A lot of people forget that the Silicon Valley has minted 100s of thousands, if not millions, of millionaires.
Housing prices have doubled in the last five years. The $1.4M houses you're looking at were $700k. If you'd come then, and bought, you'd have $700k minimum in net worth. The stock price has also doubled in that time. How much more will it go up? The ship has probably sailed for big opportunities here, but a prudent move back then, for an average Joe, might have made you FI by now.
'This factors into a related point. Engineer jobs here are a dime a dozen. It's not a fancy job. A good job, but more like a factory worker in the midwest. Regular engineers don't live in the best parts of town, or the nicest houses. The pre-IPO employees at Google live in those parts of town. The good jobs the OP has in the midwest make her family VERY well off. Not so here. I've met people who come here who have a hard time with that.
Others have touched on this, but don't expect the same lifestyle as in other places. You don't move to Paris for the big, cheap houses, or your ability to save a boatload of money. You move there for the unique things that Paris has. The Bay Area is like that. If it's not for you, that's okay. But it is very different from the Midwest. There are a lot of cool things here, like the mountains and beach, and world class city. The high today was 76 degrees, so my kids play outside. In the July and August, the temps are like 85 degrees (with some hot spells). Most of the places I've lived didn't have AC, because you don't really need it. Several of the places I've lived didn't have central heat, because you don't need it.
So the comparison to other places in terms of affordability, etc, miss the point. If you're the type of people who can make it here, it's great, and you'll be rich. If not, this place is hell on earth.
From a conventional, middle class point of view, you're MUCH better off where you are. I say that will complete seriousness. I personally know at least 100 families that have moved away because you can't make it here with a couple of kids and 2x $100k salaries. You can have a bigger house, better commute, etc elsewhere.