Home ownership isn't a good financial option for everyone, but for most consumers who aren't accredited investors it's the only way to make highly leveraged trades. You can't buy an index fund with 20:1 leverage. Of course this occasionally blows up, but even then the downside is limited.

Even if ownership doesn't make sense from a financial standpoint it's still somewhat essential for parents of school age children. Renters can be forced to move on short notice if the landlord declines to renew the lease, like if they're planning to sell or redevelop the property. This instability has a cost that goes beyond financial concerns.