Some ideas -
1. Many people are homeless and a lot of houses are not being lived in/ theyre foreclosed too easily
2. People have to pay off their mortgage the majority of their lives
3. Back after WWII, baby boom, you could attend Yale, have a nuclear family, and own a house on one family member's minimum wage. Most people now don't have a full career until they're like 25.
4. If you cant pay rent, you get evicted easily but one person working fulltime for 17$ can barely pay off a 1 bed 1 bathroom apartment... and minimum wage most places in the US is about 7-9$.