Path analysis using structural equation modeling showed that psychological insight, not metaphysical beliefs, uniquely predicted beneficial outcomes.
This makes sense as that metaphysical beliefs are fundamentally a type of delusion, regardless of their specific content. However psychological insights are fundamentally a type of increased self awareness.
Both, however, can seem profound and true to the user.
Let's use a common example of someone taking psychedelics and thinking that through the experience a deity is contacting them or that the user themselves is a deity. In the context of the way the user is viewing the world this type of thing can seen incredibly real, some people who take psychedelics end up with fantastic delusions about who they are and what their purpose in the world is. A common one is that some users will literally believe they are Jesus or Vishnu or some other figure from classic religion. Another one is that this world is fake or a simulation or a product of some hidden civilization that is leaving clues for people to find, like codes that can only be seen in laser light when the user is under the influence of a psychedelic substance. None of this type of delusional material is beneficial for the user, though it may not be specifically harmful for the person. There is evidence to support the idea, however, that in some users psychedelic use can reinforce delusional perceptions and decrease a persons ability to understand the world and their role in it.
However a great many people who take psychedelics end up gaining profound insight into their own psychology and emotional states as well as the limitations and the flaws inherent to perception itself. This allows psychedelics to be incredibly useful tools for therapeutic applications.
It seems that to some degree education and personal awareness play major roles and that users brought up in classic religious paradigms are more prone to delusional experiences that relate to their religious backgrounds or lack of awareness about things like physics and nature. A lot of this distinction seems to rest upon the idea of causality and how the subject perceives it. Those who believe that everything happens for a reason that has to do with supernatural causes, and that the universe or their own life is meant to achieve or result in some specific thing, like say enlightenment; are remarkably prone to delusion in regards to this stuff. One of the best examples is the theory of Terrence McKenna of Timewave Zero and 2012, which is best described as utter batshit. He was well read, highly intelligent and largely out of touch with reality.
One issue with psychedelic use and the user impact is that these substances make at least some people, if not most who take them, particularly vulnerable to suggestion and the quality of the information and the content of said suggestion may have a major bearing upon the end result. If said suggestive content comes from the user, it becomes autosuggestion and depending upon the ontology and cosmology of the user this may result in the development of profound and serious delusions in some people, all seemingly associated with metaphysical concepts. It seems like religious and spiritual beliefs have the greatest capacity for harm in terms of this. Moreover because these drugs are mind-manifesting, they can cause delusional beliefs to be experienced as perceptions, to put it another way; psychedelics can evoke the ontology of the individual, even if it is entirely delusional or totally absurd. Despite being utter rubbish such delusions are experienced as real by the user.
However the knowledge that psychedelics can reinforce delusion can act as a type of vaccine, that potentially inoculates individuals against the disease of delusion by allowing the user to realize that psychedelics can make things that are not real seem more real that reality itself does. At least this is my understanding of this topic. Psychedelics are better at helping us see ourselves and gain insight into our patterns of behavior and belief than they are at helping us understand the how and why of the existence of the universe.
This is the reason that one of the insights I tend to share about psychedelic use is that the mind cannot always be trusted.
To add a bit more, one of the issues is that psychedelics can make something feel true, it turns out that truth cannot be identified by how something feels, but Organized Religion and cable news would have you believe that if something feels true then it is... this leads to serious delusions. There are forces in our society that are deliberately programming people to conflate emotion with truth. How a thing feels is often of greater psychological importance to our species than the evidence supporting it, so religious persuasion works well upon us, but truth has nothing to do with emotion and the idea that emotional states can provide insight into the nature of truth is largely just a way to manipulate people into believing something is true when it is totally false.