One of the most interesting points about Brooks being the biggest seller in the running market to me is that they don't sell a single 'cheap' shoe (unless you count 'lifestyle' ones). Saucony, Asics, NB, Adidas, and ESPECIALLY Nike all have $50-80 'running' shoes, and most are objectively crap. Nike is always the biggest offender, as we'll get people who come in asking for anything but a Nike, because they had a terrible experience with the discount Nike they got at Footlocker or Dicks (or they bought Frees and tried to train in them).
The Pegasus and Structure are two long-running shoes from Nike that are, and always have been, high quality training shoes that are very competitive within their categories. But outside of that, there has been very little stability in Nike's lineup to build brand or customer loyalty. Maybe I should add the Vomero to that list, as they've been pretty consistent with it over the years. Most of their legitimate running shoes get a complete revamp every couple years, and highlight some new, 'revolutionary' technology that they impose on half their models, and within 2 years barely even use anymore to make room for their next pet technology project. Most dedicated hobby-joggers get apprehensive if there's even a minor update to their shoe like adjusting the location of overlays on the upper, yet Nike completely reworks 75% of their models every couple years to showcase new technologies that have no staying power. They're also, by far, the biggest pain in the ass to work with in terms of maintaining stock and ordering, as they seem to be heavily pushing direct-to-consumer sales from their online store. That's great selling to the fashion-fitness crowds who buy based on color schemes to wear to the gym, but for the 'serious' hobbyjoggers who want to actually try things on it doesn't work so well (especially when the model fit and style changes so frequently).
Nike absolutely DOMINATES the high school spike market, and does significantly better in HS trainer sales than with adults. Its not uncommon to see a HS kid try on a couple pairs of spikes, like the fit of the NB/Saucony/Brooks better, and still buy the Nike. I'd say the marketing works.