Most blogs fail for several reasons. One reason is that some people think that blogging results in instant money. To the contrary, you will need to put in a lot of time and effort into your blog before it makes money. So, you need to put in a lot of time before you will see a return.

Another reason blogs fail is because they lack focus. Meaning, if you start a blog, you want to be in a niche. There are so many blogs out there so if you don't focus on a specific niche - it is unlikley that your blog will be a success.

Another reason why blogs fail is that they aren't updated enough. So, when you have a blog, you need to make constant updates so that users come back again and again. Remember, the more times your users come back, the more money you will make.