Gold Investing - Insane? Or Surprisingly Successful?

[Scott Trench]

It seems pretty clear to me that members of BiggerPockets will generally understand the obvious long-term advantages of Real Estate and even passive index fund investing over hoarding gold.

The problem is that gold isn't so obviously awful as I originally assumed - this was shown to me while debating with a friend. Over a 30 year period, Stocks left gold in the dust:

Over the most recent 15 or ten year periods, this is not the case - and 15 years is still a reasonably long time frame! Check it out:

Now, I perceive gold to be a terrible investment, because when I think about things practically, gold is a rock. (I know, it's a metal, but come on). A rock has no value, produces nothing, and just kind of sits there and shines.

How would you go about disproving a gold enthusiast, and showing them how unwise it might be to bank their future on accumulated gold, vs businesses, land, debts, and other things that provide real value to the economy and human life?

How do you convince the gold investor he is unwise, when he throws this second 15-year chart in your face?