Judging by how many Gerber knives I see in everything from REI to lots of big box sporting goods store, I suspect they sell more knives than Spyderco or Bemchmade.
Your statement is probably true. But it is not how many knives a company sells that is important; rather, how many owners of those kives remain satisfied with their purchase years down the road. Quantity does not always equal quality.
My main problem with Gerber, as many others have stated here, is that they most often fail to print on the package what blade steel the knife is made of. Would I buy a can of soup that did not have the ingredients listed? I feel that Gerber does its customers a disrespect when not listing the blade steel. If you're cool with that company attitude, then so be it. The customer puts up the money. The customer deserves to know what they are getting.
And some seem to think that they are a good knife at their price point, but if I pay ten or twenty dollars more for another brand of knife that will last me twice as long under use, who's really saving money? In the long run, you rarely save money by buying cheap, because cheap products often wear out or break in less time than a better made (and initially more expensive) item. And when a knife fails, it can cause injury to the user. If the lock fails and the blade folds shut on my finger, I may need stitches, and that will definitely cost me more than if I had initially paid more for a knife with a better lock design.
And I don't think Gerber expects one of their buyers to be all that knowledgeable about knives or wilderness survival. They play to the uneducated consumer. If you can watch Bear Grylls give himself a water enema (here you go:
http://www.youtube.com/watch?v=TtIG4TuVnvg ) and you then want to rush out and buy a knife just because his name is on it, go ahead. A more educated consumer will realize that a true knife designer such as Ethan Becker probably knows a lot more about outdoor survival and actually designs the knives bearing his name appropriately. And he's on this site: you can literally go talk with him over in the Becker subforum. Anyone here from Gerber? Nah, as a manufacturer of knives, they can't be bothered with folks who are passionate about knives. Your average knife buyer at a big box store probably has not taken much time to learn the roles of a knife in a survival situation: do I need carbon or stainless, are serrations a plus or minus, is this blade length adequate for processing firewood, etc. They will buy a Bear Grylls knife because they think it looks cool and is endorsed by Bear Grylls. That same 50-60 dollars could have bought them a much better survival blade if they had taken the time to look online or at a true knife shop. But they were already in Wal-Mart to buy dog food, a new toothbrush and the latest Lady Gaga CD, so they pick up the Gerber. They don't care about the warranty or customer service that Gerber gives compared to different knife companies. But they'll learn the hard way on that one: through experience. A bunch of us, myself included, bought Gerber knives when we were younger, broker and not-so-educated. Do I still buy Gerber? Nothing in the last few years. Maybe Gerber's only current compliment is that it does at least introduce new comers to the world of knives.