Storing your wealth in the form of a house.

People talk about building equity, but they never bring up (a) rising house prices is a recent phenomena, and (b) housing prices crash every 7-11 years. They look back only 40 years, and they simply ignore all the crashes during those 40 years.

It's especially frustrating to talk to people older than me who completely forgot that the Great Recession happened. One real estate guy (who's almost double my age) had the audacity to argue that house prices never go down -- he of all people should know better.