In what world can someone making $25k/yr (according to your graph of the 20th percentile) afford rent, cell phones, internet access, large screen tvs, dvrs, cars, refrigerators, dish and clothes washers, etc.? In most metropolitan areas just rent will eat up half of that, health insurance much of the rest, and a car all the rest. And don't even think about trying to buy a family with kids health insurance -- the average family health-insurance policy costs $13k/yr, and even a bare-bones policy costs around $5k.
Outside of a metropolitan area, it's easy (I've done it, and had plenty of money to spare). Inside of a metropolitan area it's a lot harder and probably requires roommates or living in the suburbs or finding a particularly cheap area to live.
This may sound trite, but it's easy if you stay single. When I graduated college (in the middle of the dot com bust), I made $30k at my first programming job. I lived in a cheap ($525/mo) apartment in Houston and drove a used car which was paid off. Not only was I able to live comfortably (see a movie, buy a cd or eat out whenever I felt like it), I was also able to pay off my student loans at an accelerated rate of $500/mo. Subtracting just the student loan payments would have put me at an equivalent salary of $24k.
That being said, I can't imagine raising kids on that wage.
I mostly agree, and I didn't feel particularly poor when I was a grad student making $24k/yr either. That was $24k with health insurance, though, which is probably another $5k value if I'd had to buy similar insurance privately. Also, I didn't have a big-screen TV, dishwasher, washing machine, or dvr, though I did have a cell phone, internet access, and refrigerator.
