you don't have to be "investing" in an asset to have exposure to that asset.
you have short exposure to an asset iff: asset value up => your utility down. the opposite is true of long exposure.
by owning and using a car, you have a short exposure on gasoline. gasoline prices up => you are worse off. you're not "investing" in gasoline, but you still have an exposure.
you have a "natural" short exposure to housing because if you do not buy a house and housing prices increase, you will be worse off. if you rent, housing price increases will drive rents up, and if you are going to buy a house, the amount you have to pay for your house will increase.
by buying a house, you become housing price neutral. if you already have a house, then an increase in housing prices doesn't make you any better off - even though your house is worth more, so are other houses.
you have short exposure to an asset iff: asset value up => your utility down. the opposite is true of long exposure.
by owning and using a car, you have a short exposure on gasoline. gasoline prices up => you are worse off. you're not "investing" in gasoline, but you still have an exposure.
you have a "natural" short exposure to housing because if you do not buy a house and housing prices increase, you will be worse off. if you rent, housing price increases will drive rents up, and if you are going to buy a house, the amount you have to pay for your house will increase.
by buying a house, you become housing price neutral. if you already have a house, then an increase in housing prices doesn't make you any better off - even though your house is worth more, so are other houses.