Is your home an investment?

I've seen it argued that while it may be a poor time to buy investment property in Vancouver, it's never a bad time to buy a home you live in because 'your primary residence is not an investment'. While its true that your home will never be as liquid as stocks or a high interest savings account, it seems disingenuous to claim that your primary home is not an investment, particularly when the next reason to buy now is often that 'prices always go up in the long run'.

If the hope for future price increases isn't an investment than what is it?

According to this article the average house price in Vancouver for November was $519,294, down about $29,000 from the previous month. Now I don't know about you, but anything I buy for more than a half million dollars is going to be a fairly major purchase in the grand scheme of things, and $29,000 represents some nice renovations, a chance to buy more space or a few really nice vacations.

Maybe I should be unconcerned about the historical ups and downs of the real estate market since my home is not an investment, but if its not an investment then why is it so much more expensive to buy then it is to rent the same property?