XRP is not a cryptocurrency.
How can you say that? And from what site did you learn that Ripple (XRP) is not a cryptocurrency? I do know that it is a system created specifically for financial institutions while its coin (token) was given birth through ICO, when they were just gathering funds for the project. Anyways, to enlighten you, just visit its wikipedia page:
https://en.m.wikipedia.org/wiki/Ripple_(payment_protocol)
I can say that because they have no proof of work algorithm. Proof of stake coins have no use of a blockchain and are as much cryptocurrencies as fiat would be if banks published all the transactions for everyone to see every 10 minutes.