[H]ousing wealth of U.S. households at the end of 2008 was 25.4 trillion dollars. Housing wealth is about one half of total household net worth (which is 52.9 trillion dollars), and is larger than the Gross Domestic Product (14.4 trillion dollars). Moreover, since financial wealth is more unequally distributed than housing wealth, housing wealth accounts for almost two thirds of the total wealth of the median household.
Housing as the driver of America's savings vehicle is no accident. Tax policy guarantees housing prices will always increase absent extraordinary circumstances. In fact, tax policy is so potent in this regard, what brought about the 2008-2009 financial crisis wasn't some unexpected event but the overuse of this magical money-making machine. (Like most sure things, the main threat is overloading and overextension of the thing itself.)
The issue isn't just the well-known mortgage tax deduction, which cost the government about $70 billion in 2013--it's the way it favors banking dependency and excessive borrowing. You can deduct all of your mortgage interest up to $1 million in principal on the home in which you live, which means banks and buyers are incentivized to borrow as much as they can up to that limit. By setting a limit by fiat, the government has encouraged everyone to game the system up to that limit (a corollary to Goodhart's Law). What's worse is the government compounds the problem by guaranteeing the borrowed money indirectly through agencies like Fannie Mae and Ginnie Mae. Meanwhile, homeownership rates in the U.K. and Canada are similar to the United States, even though the first two countries don't allow such a tax loophole, er, deduction. (Anything that allows you to minimize your taxes is a "loophole," but if the government likes a loophole, it'll call it a deduction to make it sound nicer and to encourage its use.) Why set up tax policy that confers so much power to the banking system?
First, in theory, it makes sense to support home ownership. Owning a home is usually a long-term decision that creates more interest in sustaining your surroundings. The reality, however, is different--as cities have become larger, community becomes difficult to achieve, and most Americans tend to be private folks anyway--they may bring an apple pie to a new neighbor, but unlike many other countries, an invite into one's home is rare.
Second, by having so much wealth held illiquid and therefore captive and subject to fees (broker fees, closing costs, etc.), which discourages impulse moves, the government can manipulate its citizens' financial freedom and also its currency strength. In contrast, in other countries, especially China, residents can remove their wealth--such as stock market gains--and transfer it elsewhere, such as Canada (Vancouver) or the United States (Cupertino, CA). Such options can create havoc for governments, because not only do they lose wealth that supports their own currency, but the wealth they helped created is now captive in another country's currency and protected by law, making its return more difficult.
Third, if wealth is illiquid, easily tracked, and tangible, it can provide stable tax revenue. How does this help the average resident? Under a cost-benefit analysis, it doesn't. In California, even after passage of a proposition that limited the government's ability to raise property taxes, some local governments still tried to over-estimate housing prices for purposes of increasing the applicable tax revenue or granted more developer permits than usual, harming quality of life by not accounting for public transportation or improved roads or new highway lanes.
At the end of the day, globalization requires more flexibility, more consumer disposable income, and more individual labor mobility. Meanwhile, America's tax code continues to prioritize the exact opposite. What could possibly go wrong? (Again?)
Bonus: the key to currency strength is reserves, and when your non-gold and non-natural-resource reserves are guaranteed to grow as well as be held captive, the (financial) world is a reserve bank's oyster. In normal economic circumstances, if you want to make your exports more attractive, you can weaken your currency by issuing more debt; if you want your currency to remain strong, you issue less debt or debt at ultra-low interest rates. In America, however, you can have the best of both worlds--you can issue more debt, keep it captive in housing, and create tax policies that ensure the debt becomes an asset at some point. How does this captive wealth, which allows greater government manipulation of both currency and exports/imports, help sustain a growing middle class? Well, it doesn't. It actually leads to more boom-bust cycles and debacles like the 2003 Cancun WTO trade failure and its continuation. Rendering the sale of essential items like housing and education on the financial sector's willingness to issue debt is a recipe for short-term gains and long-term disaster.
Worse, by ensuring both private and public banking entities have disproportionate influence over the economy, you cede power to the financial sector in the absence of almost perfect regulation and enforcement. What does the financial sector do in exchange for such power, given that it doesn't make anything? In theory, it exists to encourage stability, predictability, and the integrity of economic transactions. Unfortunately, with pro forma accounting and conflicts of interest within banks, it doesn't even do accounting or valuation well. In short, America's current tax system takes a sector that should be the designated driver in the economy and makes him or her into a Formula One fan itching to get into the driver's seat. Given the global nature of finance, it's not just America that falls prey to such problems--google "Deutsche Bank hidden losses swaps" for more.