Why Do We Buy Homes?

Modeled Behavior doesn't understand why we don't just sign longer leases:

I suspect that people want the collateral value of the home. That is, they want a large piece of property that they can readily borrow against. When people say owning a home provides security, what they really mean is “the ability to take out a second mortgage when things get rough” provides security...I am not sure what the implication for this are but it seems to me that it represents some type of dysfunction in financial markets or human discounting. Why is it better to accumulate a security through home equity rather than savings?