Because the world needs more gadget blogs

The page "What Your Blog is Worth" has an interesting scatterplot attempting to show how much traffic you need in order to make some amount of money with blogging. He bases that solely on annualized income from BlogAds, using the prices various bloggers charge and how many ads they have running.

Even if we assume that BlogAds is correctly provided an up-to-date number of ads being shown, there are a few other factors to consider. For instance, BlogAds is certainly not the only possible source of income from blogging.

A few others include: AdSense, Chitika, and affiliate links. Unlike BlogAds, the revenue possible from those is open-ended: you could earn nothing, or you could earn a good amount, and perhaps even more than from BlogAds. In the first case, you get money per click whether or not someone buys something. The middle case is similar but (I believe) more stringent. In the last case, in most cases the user needs to buy something. But, if they spend $100, you could get a fair commission.

If you run a gadget blog about, say, digital cameras, and people find your blog in searches, they might be more inclined to click on a Chitika ad or an Amazon link allowing them to buy a camera. There are many affiliate programs and Amazon carries a wide array of products, so if you attract visitors either through searches or through links elsewhere that are interested in some specific niche, and there are products in that niche, people might consider buying those products through your links. Another example might be an authoritative book review site that people visit specifically to read your in-depth book reviews. If you say a book is good, you might get a reasonable percentage of your visitors buying that book through your Amazon link.

On the other end of things you could get a large amount of unfocused garbage traffic, and figure that a certain percent of those would be interested in your ads.