[Ghoulish Delight]

In terms of "messing with chemisty", I'll got out on a limb and suggest that the amount of "damage" (i.e., irreversible alteration) done by the huge dump of adreneline (and countless other hormones) during something like skydiving is likely a far larger chemical alteration than is done by LSD where one dose is so small that, as a percentage of liquid volume in your body it's literally zero.

I can totally accept, "It doesn't seem like something for me." That was me for a long time, and still is for many-a-recreational substance. Such things certainly aren't for everyone. I generally don't set out to try everything I can. But "I don't want to mess with my body" (especially with "except for caffine, sugar, chocolate, and adrenaline sports" caveats) is an interesting bit of excuse making.

As for hallucinations, I've never had a true "seeing something that's completely not there" hallucination. What I tend to experience is an easing of my minds visual slipability. My brain, under the influence of certain drugs, likes to take what I see in front of me, turn it into a mental image, and then alter that mental image in vivid and interesting ways. I don't see things that aren't there, I see things that are there in a visually enjoyable way.

Actually, one of my favorite states is towards the end of a shroom experience in what I like to call the "what's different" stage. The vivid visuals are gone, the scattered thoughts are gone, but something just feels different. Just enough to give the world a fresh perspective for a little while. The best analogy I can think of is when, after many days of rain and cloudiness, all of a sudden it's a clear, sunny day. Nothings really changed from the last time you saw the sun shine, but the familiar still seems new and wonderful.