While it is important to find something that you love to do and turn it into a money making business, you do have to be cognizant of the return as you pointed out. There are many opportunities that I found and tried out that at the time seemed great. But when I took a step back, I realized that I was working a lot for very little income whereas other things I love doing brought in much more money.
If you have specialized knowledge in a certain topic, you can put together an online course to teach others. For example, if you have experience in real estate investing, you can create an online course “Real Estate Investing 101”. The benefit of an online course is that once you create the course material, you can sell it to as many people as you want.