People have been investing in houses for income and profit for many decades in America. Some people rent them out and act as the landlord while others fix them up and sell them. Of course others- contractors and builders- build them on spec or customize them for clients.
But in the past twenty years, this has gone to another level. Interest rates (and low inflation) technology, and law influenced by societal practices, have turned houses into valuable investment assets- for capital gains and for income.
Low interest rates make Treasuries safe investments, but are unproductive safe havens. Perhaps the United States won't go broke- but it won't pay you much for your money, either. Single family homes- and real estate, more generally- has become a substitute safe haven asset to provide income, while protecting (and, hopefully, growing) capital. Further, low interest rates offer less risk for investors (a/k/a flippers) who pay little in debt costs while the home is improved. And because interest rates are low, a potential buyer may be just around the corner.
So, low inflation and the resulting low interest rates and low Treasury yields have turned houses into investment vehicles- for everyone.
But it isn't only interest rates- it's also technology and laws.
Renting houses as short term vacation properties- or as hotels- would not fly in prior decades. It violates zoning laws and state licensing laws. A house can't be used as a hotel any more than it could be used as a restaurant. But the proliferation of this activity, as promoted and scaled by companies such as Airbnb, combined with the decline of the hotel industry, due to health concerns and as caused by the proliferation of Airbnb-type house rentals, has pushed the law- state and local laws- into a direction of accepting and licensing the use of homes as short-term rentals for vacationers, as long as certain rules are followed- and certain taxes are paid.
In sum, houses are Treasury and safe haven alternatives and hotel alternatives, turning houses into investment assets, and not just homes. As long as low interest rates continue to incite a hunt for yield and asset inflation, and as long as zoning laws in residential areas are compromised by law makers, themselves, these trends will continue to grow- as will their negative implications for affordable housing and for the hospitality industry.