Most people I know only buy Ripple because of greed. Because it might be a good investement. But don't be fooled, a strong Ripple is bad for our crypto market because it makes a massive manipulated and centralized shitcoin stronger as is should be. We need strong decentralized coins such like Bitcoin, to be strong. 
Bitcoin is already strong. Even more so than Ripple. While that's the case, we shouldn't underestimate the power of whales and "Wall Street". Most investors don't care about decentralization these days, so they will pour money on any coin as long as it's able to make them lots of money in the long run.