How was Kylo Ren successful? Arguably he lost the most in The Force Awakens. Starkiller Base blew up, he was defeated by Rey in battle, and was unable to find the Luke Skywalker map. He only had two successful feats in that movie, which were using Starkiller Base for the first time, which was really Hux's victory because it was the general who suggested demonstrating the power of the base, and killing his father, which was like a minor victory at best.
Sure, in later movies he would be extremely successful, such as becoming the Supreme Leader in the Last Jedi, but he only really lost things in the Force Awakens.