Warning messages can be good advice for those who will make a transaction at a high cost. Although Ethereum wallet shows the transaction cost before making a transaction, you can check it below the receiver address. Who has huge money, don't care about the transaction cost then these things happen.
I think that before we wanna try to send a transaction there was a notification about how much we will send and the fees, The sender was not doing a double check to the his transaction before try to broadcast it into the network.