Michael Prescott started a discussion on psychedelic drugs and how they may just produce hallucinations instead of genuine experiences of non-physical reality like NDEs. He provided a number of examples of bad trips and experiences with insectoids and reptilians and contrasted this with the fact that there have only ever been a handful of reported hellish NDEs. He admits to being biased against psychedelic drugs and not being particularly interested in investigating further (though he shows some more interest toward the end).
The problem I have when reading about these bad trips is that the people usually seem like jerks and bums. They like doing drugs recreationally, looking for a trip rather than insight, they are generally dismissive toward the cultures that use them for spiritual purposes, they hang around with jerk friends, seem like moral relativists, and just exude an air of jerkness. It may very well be that when you pierce the veil of illusion and you're living a crappy life the entities on the other side admonish you to get your act together.
Regarding insectoids/reptilians, earth insects are just as real as earth humans, so why should spirit insects not be as real as spirit humans? I would expect the vast majority of non-physical worlds to be inhabited by non-humanoids. Especially in the lower worlds, where the more malicious or jerk spirits live.
Maybe this is a way of punishing people who reach too far for things they are not ready to possess. The universe is set up in such a way where one cannot gain without giving something up. One cannot gain the Truth without giving up the illusion of the separate self, and when people want both that's like trying to put two north pole magnets together – it just doesn't work. There's a reason people train for decades in preparation for genuine mystical insight, and why only a few thousand people at any one time really put the effort into it at all. It would take the average person possibly billions of years in lower spiritual worlds (which may be very nice heavenly worlds by earth standards, but they're still illusions, just nice illusions) before being able to ascend to the higher formless worlds. When people try to get the Truth all at once without doing the work of preparing their minds to accept it maybe a mechanism is in place to bring forth these more horrific entities. They still get shown the Truth, or as much as they can take in, but they also get kicked in the teeth for trying to fly too close to the sun.
The Truth is itself very traumatic to anyone who is not prepared to receive it. In many of the stories of bad trips the people are all heavily invested in the ego, they all want to pursue a life of sensory gratification, of worldliness, and at the same time they go and reach for the Truth, but the Truth is not material, it is not worldly. People are traumatized to suddenly experience that this life isn't real, that the separate self is a fiction the mind creates, that all this egoic worldly stuff is a lie. It's completely natural to feel broken down, like your life is worthless, when you see you've been going in the wrong direction all along, running in circles, chasing after illusions. It takes a lot of training to basically get over yourself enough to make the mind ready to accept the Truth, and to have the ego boundary shattered all at once, while being heavily invested in the lie, is going to be painful.
Now here's Ken Wilber discussing psychedelic drugs for 18 minutes.