The definition of stablecoin is, that USD or any other fiat backs it.
This is free market, everyone can launch their own project whether it'd value depends on its demand and supply or like USDT, its value is pegged to USD but we never know the creator actually has reserves for the printed tokens or if they just do it out of thin air that's why it's not suitable for holding and people mainly uses it for trading.
And that issue is never dying for Tether. I have no updates if it's already done or they're able to prove their claim that they're 100% backed and has that reserve on their vaults. But for the likes of other stable coins that are made by centralized platforms and exchanges, they've got the eyes of the regulators hot on them and that's why they have to comply. I am not saying to choose them but each of them can have their own issue if it's about backing their own reserve so, choose wisely if you're going to keep your money in stablecoins during this bull run or with any season of the market.This is free market, everyone can launch their own project whether it'd value depends on its demand and supply or like USDT, its value is pegged to USD but we never know the creator actually has reserves for the printed tokens or if they just do it out of thin air that's why it's not suitable for holding and people mainly uses it for trading.
But if people wanted to avoid the downsides of fiat, why would they peg their crypto to fiat? Do they not understand why it is important to get rid of their Fiat in the first place? 
1 BTC = 1 BTC.
Well said, money is safe and sound if it's in BTC as it's the actual money.1 BTC = 1 BTC.