I am learning web development. I finished a PHP class and am now taking a javascript class.

I would like to combine the 2 skills, web programming and internet marketing.

I don't know a lot about internet marketing. From some videos I watched about the topic in general, content marketing may be a good start. I had an idea to make some financial calculators. I know such things already exist. So I would start my making some basic calculators, like calculating a car payment based on user inputs. Then get to more unusual calculators, like for buying a duplex, living in one unit and renting the other.

Anyway, that part I could figure out. Then I'd need to do seo. But what about monetizing? I see that other content only sites have ads. Is this really a viable business? I can see how it would be pretty passive income once built, aside from maintaining seo.