Why peoples want to become a blogger?
If the time they spent in the blogging are used in other profession then they may have got a fixed monthly income but they still sticking with their computer screen and typing all the time, tweeting, commenting, digging, stumbling, reading the popular bloggers success and many more activities that gains traffic, popularity and quality content to their blog.

But to reach in the position of high earning money from the blog, you must reach to that level that the blogger like Darren of Problogger or the Yaro Starak of Entrepreneurs-Journey.com . These mentioned bloggers earns more than $10,000-$30,000 per annnum, which is really a big amount. Just think if you live in India and you earns $3000 per month then you will receive around Rs. 137,399.56 INR. There a blogger named Harsh Agarwal of ShoutMeLoud who earns such amount of money through blogging.
I can't say that only the popular bloggers earns money but the money also generates by the small bloggers too... they use Adsense, Chitika, and others different Advertisements and combines them to receive a sufficient amount of money. But do you think that earning a normal amount can compare with your Salaries? And who knows that later in the future Bloggers competition may keep you back and unsuccessful!
So, the money is generally the main thing that the bloggers wants to achieve in his or her blogging carrier. But in spite of money, the blogger also wants Popularity, Followers, Interviews in many popular blogs and at last but not the least- The Quality Contents.
I just want to say- always write the Quality Posts on your blog, so that your readers starts trusting on you and always ready to do anything for you- even can buy your products.