Quote from 007Arb:
Less than 5% of U.S. households are millionaires when you only consider liquid assets (excludes real estate)
If you are debt free, live in middle America, and share the most common trait of millionaires (frugality) a million dollars should do the trick.
Edit: I should add the above is for a single person who also draws Social Security.
I guess Altucher never read The Millionaire Next Door.
His numbers are so far off base it is humorous. Housing costs for example. Uhh, what happens if you have no mortgage. And so on. Every number can be ripped to shreds.