FIAT has no real backing either. The only difference between tether and usd is the issuer. USDT is issued by bitfinex, USDT is issued by the FED. Both are backed by nothing. Till now, the authorities didn't care if USDT was backed by USD or not so why should we care if the real owner and the issuer of the FIAT (the FED) doesn't?
Fixed supply of BTC kind of matters but it is not always a good thing. Let's say it has its advantages. Would you rather prefer to invest in a non-fixed supply coin like ethereum? That's way more messed up.
The problem I see here is we are at the mercy of this printer owners / central issuers, if Bitcoin had more organic growth backed by usage it would be much more resilient to price control / bubble bursts.
It would still be backed by government printer, but it's less probable that their printer will be shutdown.
I get your point but the FED and the government should worry more about USDT. I used to think and worry about that a lot too but then I stopped caring for this exact reason. If the owner of the real FIAT doesn't care if somebody where printing fake FIAT, why should I care?
Another possible reason for that is, they are willingly letting bitfinex do that.
Either way it doesn't matter till it matters.
They already printed trillions of dollars out of thin air, what's another 100 billion? Nothing.