People are somehow just using one BTC address per transaction meaning everytime they make a transaction using one btc address, this BTC address are now thrownaway and abandoned. They say its the best practice to avoid being traced.

Maybe these empty BTC address will soon be filled with BTC also. I heard that when you do an transaction, the btc address will have a high possibility that it can be hacked thru quantum computer due to the exposure of the public key when making transaction.