This is a ridiculous statement.
There are plenty of middle class (by Bay Area standards) folks who have bought houses in Fremont and San Pablo and San Leandro and Hayward.
In fact, even in Marin there are parts of Novato and weird pockets of West Marin (Forest Knolls ?) where this was, and continues to be, done.
They are boring places and middle class folks working boring jobs have purchased homes there year in and year out for the past 25 years. Yes, they had to make choices and sacrifice some things for other things in order to do this.
Perhaps the ability to do that is comparable to a lottery win ?