Other way around, people spend effort to find, mine and refine gold precisely because it's subjectively valuable.
That's always been the ironic thing to me about Bitcoin, is that by establishing that people can attach subjective value to things (like computer bits), it proves that fiat currencies can work too precisely because subjective value exists.
Likewise I doubt Bitcoin would ever fall all the way to $0, simply because there will always been enough believers "holding the bag" and trying to loop people into the "Internet funbux" club to maintain the value at some low (but non-zero) level.
It is true the prices can be manipulated over the short term - in 1979, the Hunt brothers made silver go from $6 an ounce to $48 an ounce before it crashed back down. Over the long term though, the value of commodities are tied to their value - how hard it is to find and mine gold, and whether people find it useful enough to exchange other valuable things for it.
If you were starving on a desert island I'm willing to bet you'd pay significantly more than $5 for 5lbs of potatoes if need be, because of their subjective value.
Likewise, people spend $$$ to mine gold because it's (subjectively) worth $90,000 for 5 lbs. If gold was as effectively rare as it is today, but easier to 'harvest' when you did find it, it would likely be worth about as much as long as all the other subjective factors still held.
Even today Saudi Arabia can pump oil for obscenely low prices (single digit USD per barrel), but it still sells near the market rate.
Also, I would recommend "Making Money" by Terry Prachet. Good book that actually explores a lot of the same ideas behind gold as the basis of a currency. In essence, the main character eventually realizes that the gold doesn't actually mean much, the true value of currency is that the society says x money gives you y goods.
You could argue bitcoin effectively has those qualities too. It also has a cost to mine which may peg its cost in the same way that the cost to mine gold does its.
The thing that worries me about bitcoin as an investment is it can be replaced easily by dogecoin or whatever-coin with basically the same properties whereas there is nothing else quite like gold.
Bitcoin is a little scam which justifies itself against the backdrop of a much bigger scam.
Gold is valuable because it takes effort to find, mine and refine. People want to exchange other valuable things for it because it is useful - dentists use it to fill teeth, it is used as an electronics coating since it conducts electricity well, and so forth. People have used gold as a currency for thousands of years, but that is only because it has traits that make it a good commodity, such as durability, portability, uniformity and divisibility.
Bitcoins have no value of this type. Which is why it has fallen from $1160 to $326, and will fall to $0.