Fiat currency is controlled by the government over which we have a bit of power (for those of us who live in a democracy).
Bitcoin is by definition controlled by those who have the power and thus the money to mine. It's a bit like democracy only that the more money you have the more votes you have.
I didn't say it's perfect, but it's not zero power.
Proof of stake is arguably even worse, but the energy required for proof of work isn't free either (and that's by design, if it was free Bitcoin wouldn't work).
There is more than double spending. Who decides how Bitcoin evolves? When new features are added, hard forks, etc. How much power do you have over that?
https://www.bitcoin.com/get-started/what-is-bitcoin-governance/#what-is-a-bitcoin-hard-fork
How ever you turn it, at best it's a shitty version of democracy.
Fundamentally money is all about trust, and I, despite all it's flaws trust my government much more than a random group of developers and miners.