Is it illegal for individuals to buy and sell U?

If you want to exchange Bitcoin for USDT to buy or sell, you can buy USDT freely, and no one will catch you. But when you sell USDT, you can also sell freely, and still no one will catch you.

The key point is whether you need to use a bank card when selling. If the money you receive in your bank account is dirty money (involved funds), then you are breaking the law.

There are no laws or regulations stating that buying and selling Bitcoin is illegal. The 9.24 announcement just informs you that trading digital currencies is not protected by law, and you bear the risks of profit and loss.

Selling coins with a bank card is not illegal; however, if you receive dirty money and the police trace it back to you, you may not be able to explain it...

The illegal aspect only exists in whether the money you receive via bank card is clean. Engaging in normal buying and selling of digital currencies is not illegal.

As long as you are an innocent victim caught in the crossfire, you can find a lawyer, or you can prove your innocence; you are merely losing a bit of money.

There is no possibility of you serving a long prison sentence.