"Merrill and Capgemini define millionaires as individuals with $1 million or more in investible assets, not including primary home, collectibles, consumables and consumer durables."
So not including your home, or things you can sell like your car, or collectible ginsu knife set. I guess they do include your self managed IRA though, since that is 'investible.'
Becoming a millionaire doesn't require an annual income of $400k/yr. Most millionaires probably make far less, (150-250k?), and become millionaires from savings over many years.
[1]: http://blogs.wsj.com/wealth/2011/06/22/u-s-has-record-number...