It illustrates: it's not the product choice that rescues the purchasing power you produced and tried to store to buy back later.
It's the price of the product.
It's not gold or whatever, but the price you paid for it.
Consider this:
Someone that buys and sells gold, is competing against those very same that try to take away your purchasing power in order to spend it themselves. Who is that: the governments, their central banks, and their entire parasites - backbone.
Why:
Because they buy and sell gold too. NOT to preserve there own purchasing power, but to get rid of yours.
Look at what central banks and their gold buddies (the london bullion market association systemic bank cartel) did over the past decades: the former SOLD their gold "reserves" at decades recordlow prices to the latter, to then buy it back at decades recordhigh prices from the former. Precisely the opposite of what you, a saver, a speculator tries.
Explanation is simple: when they see speculators buying gold, they buy gold too, in order to drive up the gold price, and make speculators receive less ounces.
And vice versa: when they see speculators selling gold, they sell gold too, in order to drive down the gold price, and make speculators receive less dollars/euros/pounds/whatever for their ounces.
And not just gold, that's just 1 example.
Now since central banks / governments have way more market data available than you (they force reporting) there is only 1 way, an in some aspect rather sad way, that a speculator can succeed: by going against the herd other speculators. When the latter are buying en masse: sell, and when the former are selling en masse: buy.