There are millions of scammers like this person, who is going to teach them a lesson? It won't make any difference, my advice is to avoid them completely.
If you need USDT you know where to find them, there is no point buying such from someone you don't know, everyone should get their coins on exchanges, do not buy from people or third party platforms that no one knows.
Do not go pass crypto exchanges and dexs that are very popular, this automatically decreases your chances of getting scammed.
Exposing them is the best revenge that you can take from that scammer. The more you make other people save from those scams, the better job you are doing. I don't think you can give them any lesson like telling the authorities etc and even if you do, the scammers may come hard at you because usually those are the people with a lot of influence and money that they can buy the justice too
By the way, it will be better if you can make a tutorial on how to distinguish between real and fake USDT as I am sure many people didn't know about it.
