Unfortunately, these days you don't even need to have anything like p2p to scam people. You could have a website that is looking "legit" but in reality, would be a ponzi scheme.
Most commonly, for many years people put their money into many exchanges, and exchanges didn't protect themselves carefully and got "hacked", we can't really know if they were hacked or they just stole our money but the result were the same.
This means that we saw a lot of money put their money as a whole, the "business" worked as intended for many years, but then one day suddenly they just stopped and took our money and left. Thats the scary part and it could happen and that type of scam is horrible.
Exchanges claiming to be hacked are just an excuse to take all the assets of their users. Just look at the several incidents that stated the exchange was hacked without any solution to restore the user's assets in total. and There are also cases of exchange founders who faked their deaths and made off with a lot of money so easily. Exchange is currently not safe anymore, many cases have occurred so users are also worried and don't want to put all their money in.
It's a profitable business for exchange founders. declared the exchange hacked, bankrupt and other things, and the case closed. it's so scary. This is the genius of a big scam, a big scam for which it is not clear whether the founder will be punished and compensated or not.