Is gold a good store of value? Yes, the best. That is why it is money.
Is all value subjective? Demonstrably not.
If all values were subjective then there would be nothing with which to measure value. Transactions happen, with the ease, speed and precision that they do, only because Gold, as the stable value, is there to measure value.
The measure in any field cannot be subjective – by definition.
Is a yard subjective? Is a metre subjective? Is a litre or pint subjective? Of course not; they are all measures and must, by definition, be objective. ‘A lot’ is subjective; ‘a litre’ is objective.
But there is more, and it is best to really nail the full concept. If a man is shoeless in the snow, then a pair of appropriately sized furry boots (a good) have an objective value. Where most confusion on the subject of value comes from is in the failure to distinguish between value, and the amount of value. Many goods have objective value, but the amount of a good’s value (bid or ask) is always subjective.
That is what people usually mean when they claim that value is always subjective. It is a looseness of thinking resulting from a conflation of concepts.
The amount of value attributed to a good by an individual is always subjective, but the only way that we can possible know that, is because money has objective value and can be used to measure the variations*.
Gold is a stable value. Yes, in a world that lacks absolutes, it is not absolutely stable (neither is a litre or kilo, or any other measure), but it is the most stable value, and by a country mile. That is why it is the measure of value.
It is only because Gold has objective value that we can know that the amount of value of all goods is subjective.
The world desperately needs a clearer understanding of money. ‘Dawn of Gold – the real story of money’ is a good place to start.
* Money is not a good, let alone ‘the most marketable good’.