I was a horny 14 year old whose tastes kept running up against the laws of physics. I discovered pretty quickly that furry artists were much more willing than non-furry artists to draw things that were impossible in real life. It wasn't long before I started adding "furry" to my searches for that reason, despite not really being into them, and it wasn't long after that before I discovered e621 and its excellent search-by-tag system. At last, no longer would I have to embarrassingly try and fail to describe to Google Images what I wanted to see. As a bonus, it wasn't affiliated with Google and didn't collect any user data if you didn't log in. Couple years go by, I keep coming back there, I notice I low key prefer the look of anthro animals to my fellow human beings when it comes to naughty pictures, think nothing of it, keep going back there. Discover the furry community which seems pretty welcoming, especially the SFW side, and their memes are hilarious. As a bonus, a shocking number of them are also neurodivergent, like me. Couple more years go by and suddenly I have a fursona.
TL;DR: came for the porn, stayed for the community.
Sometimes I look back and wonder how my life would have gone if I had discovered a different booru first, or if e621 had had an age gate at that point in time (which total mama's boy 14 year old me absolutely would have respected). It probably would've been a helluva lot more boring.