"Although there have been many attempts to corner markets by massive purchases in everything from tin to cattle, to date very few of these attempts have ever succeeded; instead, most of these attempted corners have tended to break themselves spontaneously."
Whether a cryptocurrency is centralized or decentralized has a specific technical meaning, namely whether a party is, by design, in control of the security or trust of the currency and can unilaterally make decisions. By that definition, Bitcoin is decentralized and Ripple is not.
https://en.wikipedia.org/wiki/Cornering_the_market
"Although there have been many attempts to corner markets by massive purchases in everything from tin to cattle, to date very few of these attempts have ever succeeded; instead, most of these attempted corners have tended to break themselves spontaneously."