Right. The ramen profitable calculation: $300 ~ $450 rent (single room apartment to 3 room palace in an inconvenient location), $200 a month food bill (if you eat like a single Japanese twenty something), $300 for utilities (water, gas, lights, Internet, phone, TV tax, cell phone, gym membership). No car or train expenses, since I don't need either to get to my kitchen table. Throw in a little extra for taxes/health insurance.
For comparison: starting salaries for an engineer at my company, which pays well for this region, are $2.2k a month. (And most of them live in Nagoya, which makes all of the above numbers higher.)
if you're living simply in somewhere like rural kansas, you could probably easily get by on $15k-ish.