Many Bloggers make a lot of money by just writing things about what they like. It is not about how many people read the stuff it is about how many people click the ads on the side or top of it. The way they make their money is by the companies that are advertising on their blog page. If you were to click on the advertisement then that company pays that person a certain amount of money for each person that clicks on it.
There are many people that sponsor these blogs but the best is Google Ad sense. This is a program by Google that pays you for each person that clicks on any of the ads on your website or blog. If you want to make a blog and start making cash you go blogger.com and make one for free or if you have a website just apply for Google ad sense and see if they will approve it. This really works and it is really easy to do. If you have any questions leave a comment or any other suggestions of other people that sponsor your blog.