If you think about it, any second of every day in our lives, something terrible could happen. And sometimes it does. How do you ever leave the house when there's cars, wild predator animals, bad people? How do you enter a house when there might be earth quakes? How do you operate a stove, or take a shower? Even breathing. What if there's some toxic gas that has no smell?
What i'm trying to get at, is that there is no risk free activity in life. It doesn't help to constantly think about everything that could go wrong. Instead, we should try to understand the risks and take precautions to minimise them.
With psychedelics, the way to do that is set and setting. Create / be in an environment and state that excludes as much risk as possible and is conducive to harmony and insight. Imo that's also partly what "setting an intention" is about - similar to a lighthouse, it helps you not lose orientation even when the sea gets rough.
I agree that DMT, and psychedelics in general, aren't for everyone and have to be respected. It is up to each individual to decide whether the rewards are worth the risks. Of course, one really can't understand either of these before taking the plunge

I think that for any psychedelic, it's a prerequisite to be able to give up control. For example with LSD, thoughts can get really weird and dark. The worst thing to do if that happens, is to try to NOT think those thoughts. That's like feeding trolls. My technique has been to find the humor in the situation. When i find something funny about the predicament i find myself in, a chuckle is the start of seeing beauty again.