That fake data can be manipulated by exchanger's team, so they can freely to create trade volumes even in major altcoin. It usually happens in a newly listed coin that the dev pay exchanger to manipulate it. To avoid this case, you just trade on recommended exchange or your favourite exchange and don't ever-interesting on the newest listed coin.
If you read the reply before you, they explain how these fake volume are generated. It is better to have a group of people to manipulate a coin's trading volume than the exchanges itself. Having a group of people trading with each other will look like more legit than exchanges doing them since different people trading means different traffic is accessing the exchange site. The more traffic these group creates in trading the more legit their trading looks.
I've some concerns and queries, i observed that many altcoins even some major coins create fake volume, if a project is new and initially listed on a small exchange and create fake volume it's obvious understood that they're trying to get listed on coinmarketcap, but A coin which is existed in everywhere, even big exchanges but still they create fake volume on small exchanges, what this means? Why they do that? Is everything just done by exchanges or project itself, and also that makes a clear difference in prices as compared to official price of market that makes frustrated.
They do this fake volume for the reason of increasing the exposure of their token/coins. If you are one of the top trading volume in an exchange, your cryptocurrency name will be flashed at the top of the site where it shows its top trading volume list. Traders will then see the cryptocurrency and might take interest to invest on it. Others do it to be listed on CMC for further exposure.