Need help to see if this logic makes sense and is practical

So let's say you make a website that has 1 million active users per month. If 5% of those users sign up for a membership that costs $0.50 a month, that's $25,000, $300,000 a year.

If this does work, and I'm not missing something. The only thing I'm going to need to do is to come up with an idea that provides free and membership content. As well as get 1 million active users per month.

That doesn't really seem that hard. Right?