I would not classify it as a psychotic belief. I don’t believe that there is necessarily a category which would accurately classify your belief. Descriptively, it is a deeply held belief for which you have no evidence.
Therein lies the problem.
Your belief system and thus your life is based primarily on a conviction for which you have no evidence.
Critical thinkers are constantly evaluating their thinking to ensure that it is logical and that it is in line with reality. In your case, your belief that the world was going to end, was not and is not in line with reality. You formed a conviction based on no scientific evidence. By your own admission, this unsupported belief has hurt you. You have lived believing that planning to live was a mistake. No need to plan, because you will die when the world ends. The lack of planning has hurt you in life. Planning would have made your life better.
Planning takes work. Not planning takes no work. Had you planned and done the necessary work, your life would have been better. Had you planned and done the work and then died ten years later, your life still would have been better for those ten years. The obvious question is: if planning makes your life better for one day, one month, one decade, then why would you not do what’s necessary to make your life better?
Factually, everyone is going to die. Also in fact, no one knows when that will occur. At age 5, 12, 15, 35, 85, etc. Should a parent choose not to give vaccinations to their child because he could die at age 5, 12 etc? Should we bother to provide education to children considering they might die before graduating? Didn’t every physician make the decision to spend 10-12 years studying, while knowing full well that they could die one day after graduating?
You might say that “they didn’t know for sure that they would die one day after graduating,” while you have a “conviction” that the world will end. I would ask you how you formed a conviction without evidence to support your belief.
At the time that you formed your conviction of the world ending, there were many scientists, scholars, and intellectuals with much more knowledge than you. They had lived longer, studied world politics longer, had degrees far in advance of yours. They did not form the conviction that the world would soon end. Why did you form the conviction that it would? Based on science, the best minds in the world had no factual basis to make the conclusion that you made. If they did not have a factual basis to conclude that the world would end, neither did you. In other words, your conviction had to be based on something other than logic, reason and fact.
I would encourage you to read about “magical thinking,” which is listed as a characteristic of delusions.
You need to reevaluate your conviction. By your own admission, believing that the world would end has hurt you. You do not want to do anything in life to hurt yourself.
It would be wise to talk this over with a good therapist and unlike in the past, talk openly with your therapist about that fundamental conviction which lies at the core of your belief system. Good luck and please don’t hesitate to write with further questions on this issue or on others.