There's a huge generational shift going on. It used to be that everybody owned a home, often starting in their 20's but definitely by their 30's. Now more and more people are still renting into their 30's

Housing costs in America have gone through the roof, so it's much harder to afford a down-payment. Also, it's generally said that millennials place a higher value on mobility and prefer to live in urban cores, where more of the housing is rentals and there are fewer single-family homes.