There are two methods by which the political system has transformed what would be bug-eyed lunacy for any other investment into a kinda-sorta safe bet (except, of course, for when prices collapse and blow up the economy).
First, demand is upped by directing mountainous subsidies toward homeowners. The most prevalent is the mortgage interest rate deduction, which racked up a bill of $100 billion in 2009, but there are also other, more subtle subsidies provided by federal mortgage insurance agencies and the federal mortgage-backed security agencies.
Second, there are thousands of local supply-side constraints that drive up the price of housing. Combined, these two enterprises have successfully put enough price pressure on housing that (historically, at least) ownership has paid off.
This is pernicious for all kinds of reasons. The vast bulk of subsidies go to the rich. Restricting the supply of housing increases the cost of renting.