As weird as it is to say, Chip's addiction somewhat reflects that of actual serial killers. Many start off doing petty crimes such as theft (which is reflected by random objects around Chip going missing). Then, it becomes common for serial killers to attack animals, which he starts doing pretty early on in the movie. Then, they move in towards their intended targets, which, in Chip's case, is kids.
Also, one of the ways that serial killers eventually get caught is when they start getting sloppy and don't deal with any loose ends. Chip's downfall was wrought when he "consumed" an adult man who was outside of his normal range and was smart enough to kill him from within.
When Fox gets sucked up Chip's colon, he finds Andrew and his nine-year-old son, as well as Chip's dog, completely alive - only, they've been surviving off of Chip's shit, and, in Fox's son's case, he's been doing that for years. By the end of the movie, he's placed on a stretcher. How malnourished was he from eating waste all that time?!
There is also the fact that Fox's son has spent his formative years stuck inside a man's ass, can barely speak, thinks eating shit is completely normal, and has no concept of the world outside of that, and he doesn't recognizes his parents. While the ending has him safe with his family again, how difficult will it be for him to adjust?
Fox's theory was that Chip was sucking children, animals, and objects up his ass and digesting them. This turns out to be completely wrong, since at least two kids and a dog are alive within Chip and there are thousands of objects completely in tact. While this means they are alive and able to be rescued, this also means that, if no one had discovered Chip's secret, they probably would have slowly starved to death. Alternatively, if he never stopped, Chip's vast colon would inevitably fill up with corpses and objects until he exploded.
