"Brony", the term, definitely originated on 4chan (There's a screen cap of the post in question out there.)
What I always got from it is people thought it would be terrible, so they watched it to make fun of it, instead finding it was actually quite well done. This would be in early 2010. Then sometimes later, around the Winter Wrap Up episode which debuts the first musical (Which has an amazing level of quality and effort put into it.)the show turned out to be fantastic and unique, and thus the fandom exploded in every direction simultaneously when said musical went viral.
I originally hated the show on principle because like, It's aimed at little girls and I'm a man! Any man that likes it must be a bad person! Also bronies are weird and should all die! Logically then I was doomed to eventually watch some of it, since in my mind I had to be this pandoras box that would magically make me a worse person if I enjoyed it.
So I watched the pilot, and enjoy it I did. Over the next 3 days I basically went through the whole damn thing on a binge and then engaged in some retrospective. I enjoy the show, a lot, does that make me a bad person? The answer is no. It was wrong of me to think that way. I think it made a slight improvement to my life based on that. I've smiled a lot more since I watched the show, become a little less up tight and judgemental.
So yeah basically we went down the same path, it's weird. I'm really happy that this show is making Hasbro megabux and will probably run for a good long time.
Furthermore I'm legit curious to see what they are going to do with Twilights character now that she's a princess. One of the things that makes the show special in my opinion is that the characters develop over time, examples of this being the obvious (Twilight getting more powerful with magic and becoming a more skilled leader over time) to the subtle (Everybody gets a pet, said pets become an episodes plot. Luna comes to grips with her duties, and later enters somebodies dreams to help them, Fluttershy slowly becomes more assertive, eventually culminating in her telling Discord off, etc.). I can't really think of any other cartoon that does this, except maybe Avatar. Canterlot Wedding/Crystal Empire are together at least as well made as any given Disney movie from the 80s/90s, and I have to give Meghan McCarthy megaprops for screwing with conventional gender roles in them.
I could literally write pages and pages on recurring elements and character development subtleties going on in the background.
Also that plushie noise that occasionally is used when somebody smiles makes me giggle literally ever single time.
If you were able to send this post to me two months ago I would probably have gotten mad at my future self for becoming "One of them". It's been an odd couple of months. I literally do think the show has layers and layers, and is (in a small way, a subtle way.) revolutionary. It's not a great work of art that changes the direction humanity is going in, nor is it anything to base political treatise on, but it is special.