You want to be unpopular at an Australian barbecue? Just tell people that their property obsession is nuts. Want to get lots of hate mail? Do it in an article for a national masthead.

Maybe I'm a glutton for punishment, but my conscience won't let the property boom continue unchecked without me speaking up to tell those contemplating an investment property that they're probably about to make a mistake.

And let's get this out of the way - I'm a shares guy, I work for a company that sells memberships for advice on shares. Does that make me conflicted? Maybe. Does that mean I'm wrong about property? I doubt it. And I'm on record as doubting plenty of ASX-listed companies, too - so I'm not here to say that all shares are better than all property. But feel free to take what comes next with a grain of salt - I reckon it's still a pretty strong case.

Before I get to the heart of the problem, though, let me say clearly that I'm not in the property "bubble" camp. A bubble, by definition, ends with a bang. It's not impossible that happens with Australian housing, but I don't expect it.