Although the credibility of the story is in check, the message is clear still that greed is dangerous and can make you loose all your investment if you are not cautious. It is an attribute not to be accommodated unless it can be met with strong thinking to ensure that the drive that greed brings does not make you make a wrong decision. The greed that most people have is what makes them more prone to becoming victims to scammers who know how to always entice and lure these people.
Yes, the story seems somewhat strange, because Bitcoin wallets do not provide support for WEB3, but the only possibility that I see reasonable is that his friend used
TrustWallet, this is a WEB3 wallet, which is a diversified wallet that can contain many coins in addition to bitcoin and can be linked through most sites .
If the wallet is linked to the suspicious site and they get a SEED then they can steal all the coins in the wallet including Bitcoin.
What about trust wallet? It's also a kind of web 3 wallet and it supports Bitcoin. Maybe this was the wallet that his friend use and his friend carelessly visit random links and connects the wallet when it was prompted. Other hacking scenarios would be if his friend enter his keys on a shady website.
So far only noobs will fall to these attempts as it was obvious already that it was a scam/hack if you have some experience in the field of cryptos. At first I wonder why the OP said his friend is greedy but I realize that maybe his friend click on a fake free crypto offers. Nothing is wrong with that, as we all love free stuffs but the main problem is that his friend only lacks of knowledge.