Bernie Sanders is one of 10 presidential candidates taking part in a Democratic debate Tuesday, July 30, at 8 p.m. ET, on CNN. Ten others will debate on Wednesday evening. He is a US senator from Vermont. The opinions expressed in this commentary are his own; view more opinion at CNN.

(CNN) I was born and raised in a three-and-a-half room apartment in Brooklyn. My father was a paint salesman who worked hard his entire life, but never made much money. This was not a life of desperate poverty -- but coming from a lower middle-class family, I will never forget how money, or really lack of money, was always a point of stress in our home.

Bernie Sanders

My mother's dream was that someday our family would move out of that apartment to a home of our own. She died young, and her dream was never fulfilled. But during her life, at least our family was always able to afford a roof over our heads, because we were living in a rent-controlled building. That most minimal form of economic security was crucial for our family.

Today, that same ability to obtain affordable housing is now denied to millions of Americans. In the United States, more than 11 million renter families pay more than half of their limited incomes on housing and utilities. Even worse, on any given night, there are more than half a million Americans who are homeless.

Though this is the wealthiest country in human history, wages have stagnated at the same time many locales offer almost no affordable housing. Make no mistake about it: this crisis is enriching Wall Street investors and real estate speculators -- and making it impossible for many families to survive.

Data from Harvard University's Joint Center for Housing Studies tells the story. Since the 1960s, when I lived in that rent-controlled apartment, the median renter's income has increased by just 5%, while the median rent payment has skyrocketed 61%. It is a similar story with homeowners, whose incomes rose 50% at a time when home prices increased 112%.