Unfortunately, it's very hard to understand how training attention in this manner can provoke dramatic improvements in attitude, happiness, and even conventional life goals. This is where a lot of the work in modern Buddhism is being done, and I personally believe we need to integrate these techniques into our everyday systems and ways of living. Otherwise, it's perfectly reasonable to dismiss them since good, objective evidence of their efficacy is hard to come by.

Perhaps a useful framing for readers on here is in reprogramming your self. We often accept that we cannot change or even that we want to change. By training our attention, we can focus it on the way the mind itself functions, and this eventually gives us the power to rewrite or rework core parts of our selves. The body contains the source code to our perception of reality, and when we can truly let go we find that we are free to be the person we want, and it is in fact our destiny.

The issue with psychedelics is that they induce these perspectives, but without an understanding of what they mean and/or why they are beneficial. What Buddhism teaches us (and what each meditator has to prove to themselves!!) is that the nature of reality is not what we think. In fact, (1) nothing is permanent, (2) nothing has substance, and (3) nothing is in control of anything else.

These three characteristics of reality are so far away from and in such contrast to our normal, everyday conception of reality, that you can witness these characteristics directly and still not believe them. It's because you are believing your thoughts instead. And that's normally fine, because they are naturally trying to protect you from what you don't understand.

Your thinking is what make the "emptiness" terrifying. That's why most meditation practices focus (albeit not always explicitly) on a balance of insight into emptiness with more happiness and peace-oriented practices such as lovingkindness and samatha. That way, when you have insights into things not being as real as you thought, you know that it's okay, but you also feel that it's okay.

It's really unfortunate for Matias, but perhaps some insight into the theory behind meditation is actually what is needed here. The thoughts about the experience are the problem, not the experience itself. The correct solution is of course whatever Matias intuitively feels is best. Perhaps this state of consciousness can never be healed/harmonized, but correcting the problematic habits of thought (not following those three characteristics) may be easier than trying to undo the entire state of consciousness. I am certainly wishing him the absolute best :)