It's hard to beat Warren Buffett for some old-fashioned fundamentals-based investment analysis so I loved his take on gold which includes the insight that if you gathered up all the outstanding gold in the world and melted it down you'd get a large cube measuring 68 feet per edge. At current market prices, the cube is worth $9.8 trillion:
Let's now create a pile B costing an equal amount. For that, we could buy all U.S. cropland (400 million acres with output of about $200 billion annually), plus 16 Exxon Mobils (the world's most profitable company, one earning more than $40 billion annually). After these purchases, we would have about $1 trillion left over for walking-around money (no sense feeling strapped after this buying binge). Can you imagine an investor with $9.6 trillion selecting pile A over pile B?
None of that is to deny that people have made money in the past betting on gold and may do so again in the future. But rather than being the ultimate hedge against risk, gold is something like the ultimate pure speculation play. You're betting that in the future more people will want to bet that future people will want to bet on gold.