The lesson of losing 350u has exposed the scam of first paying and then paying, or offline cash transactions.
There is a scam on the Internet that charges a high price first and then pays the user. Let me reveal the secret to all the novice friends.
First, the scammers will advertise through various Twitter software, telling you that they accept U and the price is extremely high, and they support payment first and U later, cash transactions, etc. When you contact them, your U is ready to be cheated away by them.
First, the scammer will ask you to buy B from the trading platform, and then ask you to withdraw the money to your private wallet. (The wallet here may be Ouyi's WB3, Coinbase Wallet), and then the scammer will ask you to try a small amount, such as 10u 20u, and first ask you to take a screenshot of the wallet balance to confirm that you have so many U, and then you can get the money.