exactly why it is not relevant to where you took this discussion. Gold = Au, a transition metal. It is an INANIMATE OBJECT.
Shares of stock are a piece of a company. A company is not an inanimate object. Comparing the 2 really makes no sense.
Accuracy is not the discussion. In your comment about "eating your capital", the future value @ T2 is the discussion. The FUTURE IS the discussion. Au has no future. Au has a price.
Value is a variable. A company can be highly valued at one time and lowly valued at a later time. Can you project the change? Let me give you an example.
Amazon in very early 2000 reached a peak. It then sold off with the dot-com bubble. At the bottom in Nov 2002, it had dropped 98% in price. Had the company changed? No. Actually it was in better shape in Nov 2002 that in early 2000. It would later explode spectacularly to the upside. But if you had planned to sell some Amazon along the way to retire in Jan 1 2000, you might not have any Amazon left in Nov 2002; at which time the later spectacular rise would have been meaningless.
In Jan 1 2000, gold was around $300 an ounce. It has risen nearly 10 fold since then. Has gold changed? No, but the value placed on gold <has>.
And this is what it's all about. Not just determining whether or not an asset will grow or not, but making a SWAG about what assets will be valued at in the future. And there is no magic wand that says you will be right.
To make it even harder, the yardstick you are measuring by varies over time. The dollar inflates over time, making the "value" of everything go up (actually, the values aren't going up, the dollar is going down in value.)