Those companies are very much outliers. Does those 3 all have development operations in Seattle?
Your figures don't seem to stack up RE Google:
https://www.glassdoor.ca/Salary/Google-Seattle-Salaries-EI_I...
Your figures don't seem to stack up RE Google:
https://www.glassdoor.ca/Salary/Google-Seattle-Salaries-EI_I...
Microsoft pays a bit less, but also employs ~30,000 people in the area.
Microsoft and Amazon are hardly an exception in Seattle - now that Boeing is leaving, they are by far the biggest employers in the region.
Housing is getting expensive, but you can still buy a small 3br for about $400K in my neighborhood just south of Bellevue, so saving $100K does sound plausible.