For example, if you take numbers from comparison tools like www.numbeo.com cost of living in Seattle is not much less than SV locations like San Jose.
But I do think it's possible to make half the salary in Seattle and still not spend 40+% of your income on housing. But I haven't rented in a while and I've heard it's getting harder.
The thing is that if you know how to live frugally, being in an expensive town for a while can work in your favor, as long as you promise yourself you'll take the money and run. If you meet Mr or Ms Right before you get out though you may well be in trouble.
a nice apartment close to work in greater seattle area is 2.4 - 4k a month for a two bedroom.
buying will cost you $5k+ unless you are putting a big chunk down, and that just seems to keep going up without missing a beat.
i would say its not possible to take a 50% cut and come here, unless you want to spend a lot of time commuting or hearing lots of sirens at night.