but this diagram of @Pooya87 does make sense.. this is trully a pear-to-pear network isn't it?  I do not find this offensive but entertaining... it is not bad to have some light atmosphere from time to time , and besides, I don't think @OP will find this offensive, do you @OP?

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Anyway, @OP if you are taking a second thought of granting your friend request, then don't do it.  Insight often saves us all the trouble, and from your post, you already have insight into what is going to happen if the source of the BTC your friend is trying to cash out is from illegal activity.