Furthermore you could use a course platform to create and teach online courses on any topic you choose — this is becoming super popular and is something we ourselves do (we have an online course we teach on social media marketing). Either way — most people typically need a platform to accomplish either of these and a blog is typically the easiest way to accomplish that (although that in and of itself can take months to years to really gain traction). We have a blog setup tutorial if you’re interested (just let me know and I’ll get you some good resources).
Bloggers are typically people who enjoy a particular topic and enjoy writing about it on a semi-regular to regular basis. If you have something you are passionate about, or are an expert in a particular area, you can consider starting a blog. Blogs are a great way to: teach people about a particular skill, entertain, or share about life experiences.