Personally, I've always liked the Psychology angle of why people are into vore.
From it being the ultimate form of being close to someone, to the "Call of the Void" psychologic phenomenon, (where someone pictures dying while doing something mundane, like driving through that guardrail and off a cliff).
Vore appeals to suicidal fantasies, snuff fantasies, furry fantasies, eating/food pleasure, isekai fantasies, magical world fantasies, so many different fetishes, stories, ideas, and stories can tie into Vore. It's got it's basis in history too, as someone above pointed out. The fact that people can connect to others about a shared fetish/enjoyment/idea, one thats tied to so many things, some of them dark, and enjoy it is fascinating to me.
Personally, I found Vore when I was a depressed teen almost 2 decades ago. Always loved dragons, at the time I had recently lost my Mom to breast cancer, Couple dark thoughts here, some why am I still alives there, and I had the thought of "What would life be like if I could be reborn a dragon?" Couple Google searches later, and now I know what Unbirth, vore, etc is. Also figured out why I really liked Crystal, Elora, Carmelita Fox, and many furry characters too. And now I had a fictional outlet for my dark thoughts and I enjoyed it. Sure, I know it's fucking weird, and I make sure no one close to me knows about it, but hey, you don't get to pick what you are attracted to.