Both, I think. For me, the turning point was the complete and utter failure of anything Conventional Wisdom had to offer. I had weight problems, acne problems, depression and brain fog and I was a loaf all the time... the depression and acne I had accepted as bad genes and the brain fog as part of ADHD, and those were things that just couldn't have been avoided as far as I knew. The weight loss though confounded me; I knew it should be possible but eating low fat and low sugar and burning 500 calories a day through exercise is HARD (it's funny, when I was trying to diet via calorie-counting, I switched out cereal for eggs and toast, and lost 20 lbs that summer. I thought it was the calorie counting, but I'm pretty sure it was the eggs now), so when someone I knew talked about losing weight by just eating a bunch of meat, I was intrigued. I switched to low-carb paleo, weight loss is happening, but the more immediately evident lifted mood and clearer mind are what's keeping me on track on in the weight department (instant gratification ftw)... for the most part. I still find sweet potatoes and white potatoes a little bit too delicious for these last 35 pounds to go without a fight.
Also, I always thought evolution was cool and had this running joke (...philosophy? both? lol) as a kid where I'd ask "what would the caveman do?"... in response to something that would come up; I don't remember what anymore (Maybe it was a good thing I didn't find it then. I might have have ended up a mini version of one of those reenactment nuts, huntin' squirrels during recess, barefoot on the blacktop haha. NTY, I was weird enough as a kid). I learned about people who fed their animals BARF diets in my teens and got REALLY ANGRY about the grains in cat food and my cat's resulting death from diabetes (which makes it even sadder that I didn't connect the dots about paleo sooner LOL). Then later, I became convinced that there were "natural" solutions to common problems, along a similar train of thought I guess, but with waaay misguided applications (almost started downing soy milk thinking it was a resolution to hormonal problems; good thing I never got around to it). Finding paleo though seemed like a natural, ahem, evolution of that thought process, haha. I pretty much had to have the details spelled out (I blame the wheat), but once they were, they made perfect sense, like how did I not see this before? sense. So it's hard to say which played a greater role; perhaps the pain as you say made me keep my eyes open for a solution, but the science interested and persuaded me. And like Anondson said, the results keep me at it.