even so called big exchangers are having fake volumes. Bitfinex, Kraken. Most of them, are not financial licensed...
It's about incentives, which exchanges do have to manipulate their volumes. However, the more reputable an exchange is, the lower the probability of severe volume manipulation is.
Bitfinex is a scum exchange. I can't find one single reason why people still use it after everything they have gone through. It's like people don't even care anymore, which they eventually will pay the price for.