As you said, its household.
It isn't HARD for two people with college degrees who both work to have a household income of six figures. Not in all fields, but in many fields, a few years of experience with a college degree should make $50k. But only 30% of Americans have college degrees. And when you are talking about a relatively young couple with two professional degrees, careers, and kids, $100k doesn't go very far - daycare and student loans are often big budget killers.
Median household income is $50k, mean - or what we tend to think of as average, is $60k. Median does a better job of taking out those $1M earners. Mean is take ten people, add up their income and divide by ten. Median is take those ten people, line up their incomes like this
4800, 14,000, 23,000, 32,900, 46,000, 55,000, 60,000, 80,000, 120,000, 1,000,000
Take the number in the middle and that is the median (in this case, take the two numbers in the middle - 46k and 55k in my completely made up example, and average those two). You get $50,500 So it doesn't skew nearly as bad. The mean in my example is $143,570. Don't get me wrong, its still skewed, but if there are lots of people at the low end (and in the U.S. we have a lot more poor people than people who make a million dollars a year), it will skew down, not up. Which isn't to say income inequality isn't an issue in our society. Wikipedia has a nice graph of household income distribution.
http://en.wikipedia.org/wiki/File:Distribution_of_Annual_Household_Income_in_the_United_States.png
The other thing to keep in mind in these discussions (and I'm not saying you are doing it) is there is a difference between income and assets. When we talk of millionaires, we are talking about someone whose net worth is a million dollars or more. When we talk of someone who has an income of a million dollars a year, that is a different thing. Most of us on this board should have a net worth of a million dollars when we retire - most of us make enough money that that is a completely reachable goal (and will be necessary to maintain our standards of living in retirement if we plan to live for some amount of time. Frankly, if my husband drops dead of a heart attack at 60, I still want to be able to travel when I'm 70. Yes, I'll miss him, but I'm not going to be my grandmother who spend her final decade sitting next to a grave with fond memories. And I sure hope he'd do the same. And yes, he has life insurance, and no, it isn't enough for me to be able to travel to Europe in my retirement if he passes on - but our savings are) Most of us will not make a million dollars a year. Making a million dollars a year makes it much easier to acquire the wealth that makes you a millionaire, but it isn't a given - you could spend every penny you make, you could give your income to charity, you could invest in pyramid scams. Likewise, you could have a small income and be a millionaire due to inheritance, savings, or just wealth (farmers and small business owners often have large net worths and small incomes)