Webinars are quite possibly one of the most potent ways you can make an exorbitant amount of money online. Russell Brunson often says that if you do a webinar every single week for a year, you'll be a millionaire at the end of it. You'll need an audience to train and you'll need to know what you're talking about. Of course, this usually requires having a website and some semblance of an online presence.
How much will you make? I think my best month with Google AdSense was almost $5,000 over the last ten years. That amazing month blew my mind since it was actually near the beginning of my blogging journey. When you go from making zero to $5,000 in a month, that will rock your world. For me, it also got me even more excited because I knew there were other ways to monetize.