Tether or USDT is a tool, something that is created to satisfy a need. That is the need for something that has a stable value (as compared to cryptocurrencies otherwise there is nothing stable) that crypto traders can use to store their capital whenever they want to exit the market or something to use to quickly and cheaply transfer funds between exchanges.
Tether is just filling a gap. It is not supposed to and it can not ever be money. There are a couple of fundamental flaws that prevents it from becoming money. (1) it has no cap meaning it can never be store of value due to its inflation (2) it is pegged to a fiat that also has no limit and has inflation.
It also can not be pegged to bitcoin because it loses its whole purpose! In other words as long as bitcoin itself exists, you don't need something that is pegged to it 1:1 and has the same value. It would make no sense.
Store of value can be temporarily but in long term and even short term like some months after pandemic, fiat currencies can lose their purchasing power a lot.
Tether is more risky than fiat currency, as it can depeg. It can be seized in your Tether wallet address but if you have fiat currency, in cash, no one can seize it except if they arrest you.
PSA: Most Stablecoins Can Be Frozen, Even in Your Own Wallets
Stablecoins: A Deep Dive into Valuation and Depegging