People are always looking for a better deal, so it is not surprising they leave more expensive cities. Here are excerpts from the first article:
"An April report from Trulia researcher Mark Uh found that lower-income households represent a larger share of those moving away from the most expensive markets than their overall population in those markets. For example, those earning less than $60,000 a year make up 27.4% of all households in the San Jose metro area, but they represent nearly half of all households moving away.Here is a table from that article.
Another study this year from California policy group Next 10 and Beacon Economics found that New York state and California had the largest net losses of domestic migrants between 2007 and 2014, and that lower- and middle-income people were more likely to leave."