Niche blogs tend to make money because the focus of the blog is on specific topics or niche. Sometimes, the blog is so specific that it covers only a targeted section- for instance, some blogs talk only about one particular car model, one type of cats, etc. From my experience in having general blog (like this one) and a blog dedicated to specific topic, I have to admit that specific or niche blogs will earn better- at least in Adsense which is my only revenue source.
This blog has been around since 2006- but as a personal blogs, it talks about almost anything under the sun- entrepreneurship, working life, crafting, creativity, blogging, family life, personality. Previously this blog also contained a number of travel articles- but I have since started specific blogs that focus on travel.
At first, I was very reluctant to create specific blogs to cover specific topics such as creativity and travel. But the blogosphere had debated largely on niche vs general blogs and many bloggers had shared their personal experiences on why niche blogs does better. In the end, I created specific blogs to deal with specific topics after considering my audience- they came to this blog because of certain articles that I wrote- they may come to read about working life and would look forward to the next post about the same kind of topic. Imagine instead in subsequent topics I started writing topics about craft business, blogging and travelling to certain places. In the end, they may stop coming.
Furthermore, if the topics covered in the blog is so diversified, it confuse readers with short attention span who have so many other blogs and sites to choose from.
Therefore, last year, I started creating specific blogs on topics such as travel to Malaysia, Thailand and creativity. Initially, there was not much organic traffic but as I add more blog posts, the traffic start to build up. This blog has been around since 2006- and yet, my Visit Malaysia blog (started in Oct last year) attracts much more organic traffic and Adsense earnings within 6 months of its creation than this blog (which has been around for a few years). My Health Blog itself provides more than 70% of my total Adsense earnings.
Still, I continue to update this blog because it is a labor of love- and some of the posts have benefited others. But I now understand that so long as I keep any blog on very general topics, traffic and earnings would not equal to niche or blogs on specific topics. Of course, unless you are a well-known public figure, only then can your blog attract lots of followers.