From the past tense in that post, I'd guess this may have been a few years ago. Today, the white-hot realestate market means living expenses are much higher.

At $120K, you're looking at a tax rate of close to 30%, which puts the usable figure at $80K or so. You want to maximize your 401(K), so your salary goes down to $65K, which is about $5K/mo. A decent 3BR with good schools (Cupertino) will run about $3500/mo (1), which leaves $1500/mo for everything else. Not doable, unfortunately.

(1) https://sfbay.craigslist.org/sby/apa/d/1500-off-move-in-book...