Buy Facebook on the dip?

Facebook beat estimates for revenue and profits but its stock was hit hard when Chief Financial Officer David Wehner said the company would increase spending by up to 70 percent in 2015. So, the question is: Do we sell or buy Facebook on the dip? My answer is I bought and here's why:

Social is a very poor description of what Facebook actually does. I mean, what is the business of "social?" To connect people? Certainly Facebook does that, but is that a business? My answer is that Facebook is a shiny object that draws users in, but well beyond social, Facebook is an advertising juggernaut.

Dado Ruvic | Reuters

The Facebook logo is reflected against source code on the screen of a computer in this photo illustration.

Facebook said their revenue from advertising grew by more than 60 percent year-over-year. Ad revenue was up 64 percent in the third quarter to $2.96 billion. In the past year and a half, Facebook's overall revenue growth has hit 50 percent or more for six straight earnings reports. Like Twitter, Facebook has been gaining share in mobile at a dizzying pace. Last night's Q3 report showed mobile represented just under 70 percent of total revenue, which was a 122-percent jump in mobile revenue year-over-year.

Read MoreHow Facebook just blew a great quarter

Nearly 1.4 billion people checked Facebook during the third quarter, and an astonishing 1.12 billion did so on a mobile device. Nearly half a billion people (456 million) checked in on Facebook only via their mobile devices.

Google's ad revenue for its most recent quarter rose by 17 percent year-over-year to $14.7 billion. In total, Google recorded a $2.81 billion profit on total revenue of $16.5 billion. The average price advertisers paid Google for people to click on their ads fell by 2 percent in the third quarter.

Watch: Cramer: Trust Zuckerberg

On the other hand, Facebook has cut supply of ads, which resulted in a big jump in demand. Facebook's third-quarter results showed they served 56 percent fewer ads year-over-year, but that scarcity drove up prices 274 percent year-over-year! Daily active users of Facebook were up 39 percent to 703 million year-over-year and mobile active users were up 29 percent to 1.12 billion year-over-year.

If you rode this stock into the quarterly numbers and now, after what I think believe was a great report, you decide to sell, then I think you need to rethink your strategy. If you sold prior to earnings, or like me, had little or no position (I owned Nov 84 - 86 call spread and was short Nov 72 puts into last night's report), then I think you have a great entry beneath $74.

Read MoreNevermind Alibaba, this explains Yahoo's rally

"Fast Money" trader Jon Najarian is a professional investor, money manager, media analyst and co-founder of optionMONSTER and tradeMONSTER. He worked as a floor trader for 25 years and before that, he was a linebacker for the Chicago Bears. Follow him on Twitter @optionmonster.