I've had similar experiences. It's a real drag and makes me feel bad about myself for being irresponsible.

Well, I think you're like me in that you learn from experiences like that, and it makes you more responsible and thoughtful about who to share such powerful plants with going forward.
It's kind of a self-correcting mechanism.
Maybe its one of the reasons that psychedelics are such a tiny, tiny niche of overall drug use.
They do tend to require a lot more thought and care to use successfully and safely, and (most) people that use them learn that lesson themselves pretty soon after undertaking the journey with them, just by virtue of the nature of the experience itself.

I remain glad that these tools aren't mainstreamed to the point that they are discussed regularly on the news or anything like that-- keep the circle expanding, but keep it in the circle--

I have epilepsy and use DMT and other psychedelics without incident. I asked my neurologist specifically about this and she said there is no reason to think there would be a connection.

That is good to know, thanks.