In my opinion, that is because of fees. As we already known that Ripple need 2 XRP for add trustline while XLM only need 0.05 XLM. Also, they both have faster time while do transactions whete XLM have less fee for add trustline. So XLM is better than XRP. In addition, XLM have so many platform that easy to use for interacting with stellar blockchain.

Jed had a long string of bad ideas that Ripple's Board of Directors refused to implement. So Jed started Stellar based on those ideas. ed wanted Ripple to do a Facebook giveaway. Ripple would not do that. So that was one of the first things Stellar did. The giveaway was generally considered a disaster. As it became clear that each of his rejected ideas were bad, Stellar pivoted to become a clone of Ripple.

The reason Jed McCaleb left ripple wasn't a huge conspiracy whatsoever as one might suspect. It was as simple as the fact that his ideas and vision did not resonate with that of ripple anymore. The co-founders and others didn't agree with him and when this kept going on, he decided to make his way out. This is why he couldn't ripple as he wanted to either, it wasn't a one-man show. 
Now, there are two types of people on the internet (as well as crypto investors) those who are of the opinion that ripple is better off without Jed and then there are those who think that losing the founder was a huge loss that ripple made. Eitherway, since both the organizations are on top of the charts, it may be said that it really was just a clash of interests and no one's loss.