It's all related to shitty on-exchange bonus structures switching from coin to coin. It shows that Bithumb today has generated 98% of all BTG volume, which is completely retarded. Asian exchanges also like to mess around with transaction fee mining which stimulates people to intensively wash trade just to make a few pennies.
I only pay attention to exchanges such as Coinbase Pro, Kraken, Bitstamp and Gemini because these are legit fiat entry and exit points with traders thinking twice before attempting to generate tons of fake volumes. Exchanges such as Bithumb and all the other shithole exchanges such as DobiTrade and ZB are an absolute disgrace to this space.
Every so often you see a brand new Asian exchange pop generating hundreds of millions in volume. They aren't even trying to hide malicious activity.