I want to be a better cook. Is it hard to improve?
Since you’re asking I assume you don’t have a lot of experience in the kitchen, which is great. No, seriously, there are a lot of joys that come from being a beginner in a craft. One of them is that since you don’t have a lot of skill, to begin with, you can make massive improvements in just a few hours of learning and training.
So to answer your question: no, it is not hard for most people to improve their skills in the kitchen. All you need is to keep an open mind, take some classes, run some experiments, and maybe get some tools from one kitchen wares stores like this one. A great cook can make excellent meals with nearly any tools and ingredients, but you’re a beginner, so don’t be afraid to spend money to get better results, or make cooking more convenient.