I absolutely love spicy food, and it’s never affected my gut. I was actually confused when I read about people getting the shits after a curry and wondered if it was a joke. I’ve had curries so hot it caused people to recoil into a coughing and sweating fit after they dipped their finger in and had a taste and I have one every other day. I feel the burning in my mouth, my face turns red, my forehead sweats, my esophagus feels weird, but (tmi I know lol) when I go to the toilet I’m completely fine. no gut pains either.
I love spicy foods and they don’t upset my stomach. Though I did eat one of those “one chip challenge” things back in the day and I did fine at the time but the next two days or so I felt like I had been poisoned. Only time that ever happened to me. You probably have a threshold too but it’s just very high. Genetics and practice helps, your gut biome critters are probably used to it too.