The Thrill of the Chase
One of the really common things you hear over and over in Dogman sightings is that they chased the witness but didn't actually catch them. Given how fast Dogmen are purported to run it seems like it would be a trivial matter for them to catch and eat a running human if they wanted to, so why don't they? Some folks speculate that it's because they're fear eaters, getting some sort of sustenance from the fear of their victims, but I think the answer is far more simple and straightforward: They just chase people because it's fun.
I've had several dogs who chased squirrels and rabbits for fun but had no interest in un-alive'ing or eating them when they caught up to them, they just liked chasing smaller critters for the thrill of the chase. It seems reasonable to think that Dogmen might derive the same enjoyment from chasing smaller critters (I.E. humans) that other canids do, which would certainly explain why so many people are chased by them but so few are actually eaten.