The "90 percent of millionaires own real estate" claim is widely cited but commonly misread. The most-referenced study (Spectrem Group) found that around 90 percent of US millionaires own a primary residence, not that real estate is how they became millionaires. The popular quote attributed to Andrew Carnegie ("Ninety percent of all millionaires become so through owning real estate") cannot be located in his published works and predates rigorous millionaire research. The honest reading: real estate is correlated with wealth, and primary-residence ownership is near-universal at the millionaire level. But for most US millionaires, the primary wealth-creation engine is employment and business equity, not investment property.