Market cap doesn't mean much at all in crypto. XRP's is high because the circulating supply is 45 billion XRP - 2500 times more than BTC, 400 times more than ETH, etc.

I could create a blockchain and issue a quintillion coins and if I manage to get it listed and sell some for a fraction of a penny it'll have a bigger market cap than the rest of crypto combined.

It says third highest in the third sentence of article.