If you are aware that your friend is the type that has the mind to steal people's money, you should be very mindful of him because you can become his victim one day, however the story would have make more sense if the person that collected the $7 was someone who is not a scammer, however I don't even think the wallet was a multisig wallet because it could be a normal wallet with fake coin or token with a dollar equivalent because if it was a normal usdt he would have noticed there is something off when they require $7 from him before withdrawal.
You've really made a very valid point of me being concious with this friend because I don't think if I can be exempted of his targets. Scammers actually doesn't regard relationships and that's why we shouldn't in any case reveal our wallet seed phrase to our relatives because people are potential to compromise as long change remains constant.
That's of funding $7 to the wallet can actually be true based on the narrative. Other way he may not had been asked to top the wallet balance before he could withdraw the sum of $ that was seem so attractive there, perhaps the $7 could alternatively be a fund for gas fee. I'm not sure either.
Karma will certainly visit each and everyone of them because what they are doing is very bad and is good that they are beginning to turn against each others.
It's always good seeing the wicked ones burying themselves. How I wish innocent people will always stay out of these scammers and let them hunt themselves just like that of my friend and co. incident.