USDT is on a major exchange and that means USDT is trusted by everyone so it can't be a scam. besides USDT is widely used by everyone to secure assets when the market is red.
Usdt is also listed on non major exchange . It's hard if will based on exchange to say that a coin is trusted or not . Usdt is not a pure breed of crypto and there are people that won't trust that kind of coins but for some it's not really a big deal , as long as we can see them being paired on crypto and most feedbacks are okay , we don't doubt on them .
Many simillar coins that have same concept as usdt but as of now usdt ranked first .
it is a coin controlled by someone, anything has control in a hands of someone or organization will have a risk to turn somehow into risk, that is why most people trust, and keep their money in Bitcoin not in altcoin for savings, people trade yes, for-profit but for the long term they only keep it in bitcoins because none is in control of it and ofc due to the anonymously
When it comes to risk, I think everything has risks, including holding Bitcoin. Even though Bitcoin is not controlled by someone, the platform we use to hold Bitcoin is of course controlled.
Likewise with USDT, Ethereum and other Altcoins. I think it's just based on the belief that the coins we hold are safe.