Google still has the dominant market share. According to Alexa.com, yesterday 43.24% of all internet users went to google.com. And this doesn't include country-specific Google sites like google.co.in, google.cn, and google.de, which are all three still in the top 20 websites on the internet.

Facebook got 28.63% of internet users yesterday. Not too shabby, but still significantly behind Google. Acccording to internetworldstats.com, there are roughly 1.7 billion users on the internet. That means that each day, google.com gets visits from approximately 250 million more people than Facebook.

When you think about the actual numbers, it starts to make sense why Google is so much more profitable.

Also, don't underestimate Google's ability to target advertising to their users. The ads they display are based upon what you're searching for, in addition to other information such as your location. Now, let's say you're selling soccer equipment, and you only have enough budget to advertise on one of the sites. Would you prefer you ad to be shown to somebody who just searched for "cheap soccer balls" or somebody who lists soccer as an interest on Facebook?

Oh, and one more thing. I just did a search for "cheap soccer balls" in Google and got 13 advertisements on my search results. How many does Facebook show per page? I just did some clicking around and didn't find a page with more than 3.

If you mention only Google.com (search engine) itself,

I think operating cost for google.com is far less than facebook due to their last server investment for video storage. As we clearly witnessed in youtube, video serving is still a costly process, for both storage and bandwidth.

And for last, Google may reach many people using Google Ads as people display ads in their websites, Facebook is limited to its users. 300 million users but still limited.

Not everyone has Facebook and everyone uses Search Engines and Google Dominating the Search Engine Industry which makes them more profitable as they have way more users. They also plastered with ads everywhere if you see the TOP 3 Results are ADs mostly which most users clicks and there are ads on the side etc.

I believe Facebook might be more profitable if they actually have ADs in the main home news feed.