Can't speak for CB, but it tells
me that someone spend a few hundred bucks to make it look bigger than it is. Just like those fake 5-star reviews on iTunes and Play Store.
A couple of hundred bucks............. 100 BTC = $100 k = Maybe someone in Bittrex played around with the decimal point on the 24hr volume part of their website whilst writing reviews on their IPAD, Iphone and Android tablets at the same time as teaching a monkey to recite the entire works of Shakespeare
100 * 0.25% * 2 = 0.5 BTC, or ~$500. That's how much it costs to generate 100 BTC in volume on Bittrex. Surely a self-proclaimed BTC day-trader would already know this. But if the math is too complex for you - go ask on slack. While you're at it you can also ask how much fake reviews cost.