Yes. It doesn't matter how many times these coins get bought or sold, they keep adding to the volume that's being generated. You can create an insane amount of volume by constantly buying and selling into your own orders, which is happening on basically every exchange. Nowadays there is a new concept called mine-by-fee. It results in huge loads of volumes to be artificially generated by people buying and selling into their own orders, all to scoop up ("mine") as many exchange tokens as possible. All this volume counts towards their 24h volumes. These exchanges have been removed from CMC because it stinks and isn't genuine volume....