Ripple, the company, holds about 60% of all XRP that will ever exist. Whether that makes it centralized is a matter of what you mean by centralized. Typically, what you care about are things like censorship resistance (who decides which transactions go in?) and governance (who decides how the system's rules change?) not who holds the token.

Ripple's concentrated interest in the price of the XRP makes it possible to do things that other coins can't do. For example, Ripple could spend $250 million on something that has no hope of producing significant direct revenue, but if it results in a long term increase in the price of XRP by one penny, that would result in significant profit for Ripple. Nobody could justify anything analogous for BTC or ETH.