Not exactly true. Fiat currency, in part, gets its value by the fact the governments can throw you in jail for not paying taxes with it. Sure, not going to jail could be a subjective preference, but pragmatically speaking, that's a big, objective value proposition for most people.
There's no "could be" here. Not wanting to go to jail is a subjective preference.
That most people prefer the same thing, does not make value objective.
If it did, Bitcoin would also have "objective value" from its scarcity, difficulty of confiscation, ease of move between borders, and many other properties which are preferred by most.