I think the imagination aspect plays a big part. I passed once when my mother was cutting open a small infection in had on my finger. It wasnt the blood or the pain, because ive experienced a lot of both in more extreme settings and never passed out. Hell, I saw a guy get opened up with a razor blade right in front of me and didnt have the same reaction.

When my mom started picking away at my index finger it started worrying about it being worse than I thought. I started thinking, "what if I lose mobility in that finger and i cant play guitar as well!?" Then I rememeber thinking, " why is there dog hair in my mouth and why am I so hot?" as I woke up face down on the carpet with my mother laughing at me. That was the only time in my life I remember losing consciousness like that and think of it like a soft reset, as my brain starting flicking all the switches back on. I cant imagine experiencing that while flying through the fucking air would be enjoyable.