If the deal is done in p2p way without any centralized platform, then I can say there's nothing to do with that. The scammer is probably an experienced scammer since he let your friend believe on what he's chatting since like you said they've been chatting a lot. I'm sure he/she's using a vpn or anything that hide's personal data/ip and you/your friend can't do anything about that.
The only thing he can do is make it a lesson for him, that don't trust anyone online without verifying it and/or using a trusted third party.
3k usd/usdt is not small amount, I wonder what the deal is, or something need to buy or just an investment or similar.
that's also what I ve though that's why I posted here
Ye, Asian scammer acted like very trustworthy and he wasn't in hurry at all, always he say no problem I can wist you and similar
He was not investing
He was about to buy amazon items like phones and so by discounted prices