Yes, it is realistic to start earning online at any age, including 50. In fact, many people have found success in online businesses later in life. If you are interested in creating online courses, you can start by researching your niche, identifying your target audience, and planning your course content. You can use platforms like Teachable, Kwiga, Thinkific, or Udemy to host your course and start promoting it on social media, email lists, and other marketing channels. My preference is https://kwiga.com/lms. As for learning, the amount of time it takes to develop your skills will depend on your existing knowledge, the complexity of your course topic, and how much time you can devote to learning and creating. It is possible to start small and build your business gradually, and there are many online resources available to help you develop your skills and grow your business.