$5000/month in Seattle is well more than doable. I live off <$4k in regular expenses, live alone in the bay area, and still drive a luxury car. When I was in Seattle, I lived off of $1000/month, lived on my own, and had my own car. That was about 4 years ago.
Google compensation is also incredibly high. $140k is less total comp than what many new grads get at Google.