From a report from RP Data, that shows a number of people made losses when sell property -- it is not true to say "as safe as houses" if you buy badly or at the wrong time or hold for a short period:
As a special feature in this report we examine the
level of gross profit or loss based on residential
dwellings that sold during the March quarter of 2012. The
results are shown in the graphs below across all sales
and also divided between homes that were purchased pre
and post GFC (before or after January 1, 2008).
Of those owners that had purchased their home prior to
the financial crisis (for the purposes of analysis we have
used the date of January 1, 2008), a lower 7.2 percent had
sold their home at a loss. A much greater 42.3 percent of
these vendors sold their home at price which was at least
double the previous purchase price.
Capital gains were much weaker for those vendors who had
purchased their home in 2008 or thereafter. A larger
proportion of these vendors recorded a loss on their sale,
with 27.5 percent of dwellings sold recording a sale price
lower than the initial purchase price. On the other hand,
only 7.5 percent recorded a capital gain of more than 50
percent compared to the original purchase price. These
results reflect the significantly weaker housing market
conditions since 2008 and the benefits of a long term hold
when it comes to turning a profit on residential property.