While Gingrich is an insider, he is also ANTI-ESTABLISHMENT. And THAT is what the people are clamoring for.
Almost every establishment politician is against Gingrich because he stands for everything they hate. The establishment politicians, both Democrat and Republican, do not want things to change in Washington. They want to hold onto their own power, even if they must do so at the detriment of the nation.
Gingrich is enough of an insider to pose a real threat to the establishment - he knows his way around. He knows where the bodies are buried. If anyone can upset the establishment apple cart, it's Gingrich. And the folks "get it", even if the pundits do not.
Look at it this way - what chance would someone have of retooling Washington if they don't even know what they are up against?
While Gingrich may not be an ideal candidate under normal circumstances, we are not living under normal circumstances. We need someone who is smart, powerful, passionate, knowledgeable, and hated by those already in power.
And the only candidate that fits that description is Gingrich.
It's not unlike a wild Old West town without law and order. The townsfolk hold their noses while they elect a gunslinger to bring law and order. Then, once the job is done, you get rid of the gunny and hire a more "civilized" lawman.
Well, Gingrich is a gunslinger. And that is what is needed to clean house. Once clean, THEN perhaps a "softer", more "civilized" person to take the reigns. You know - a Romney or Santorum.