Well, apparently Paypal wasn't able to maintain his momentum.
Even if the market moved recently, a situation where it's easier for an exchange to grow their volumes, apparently itBit was quite lagging behind:

In addition to that, I noticed the most successful trading pair was EHT/BTC.

Being this pair a crypto/crypto it's difficult to see PayPal's exchange as a crypto gateway for fiat investors, as PP would like to sell us.
Of course, if the main trading pair is ETH/BTC this means the majority of itBit users are already Inside the crypto-market, while in reality, PP would like to expand the userbase.