Notes

Ultra Instinct can be achieved in real life, regardless of what others may say. Although it is not quite as you think it is, and requires great training to attain.
Normally, when you as a human being react to stimuli, your brain processes the information, then your mind decides on the reaction. This takes more time than normal, as the nerves send signals to your brain, the information is processed, then your mind processes it and thinks of a conclusion, and then sends signals back.
Ultra Instinct is the process of acting on instinct alone, free of all restraints of thought process, it is much faster than normal human reaction and much more precise, but extremely hard to attain for your average joe.
You must know what you do to such a high level you are capable of doing it on instinct without the need of mental thought or process behind your work, in such a way you basically skip the process of your mind thinking of and reaching a conclusion.
The real life equivalent of Autonomous Ultra Instinct is the Flow state, in which there are no more distracting thoughts of any form in your mind, and you no longer notice even your breathing or hear most sounds around you due to a deep, precise state of focus on your work.
This is no easy task to achieve, humans are used to having thoughts all the time, any random thought, this state offers such a deep level of focus you are incapable of having random thoughts during it.
The flow state, or real life ultra instinct is actively practiced in the world’s most high-end sports possible, and is used by the world’s best eSports players.
Of course, you won’t have ultra-speed reactions, you are after all only human, and there are VERY hard caps on what you can and cannot do, with very serious and life threatening consequences if you break through.
For further informations do search on the internet what the Flow State is and if you want to practice it I saw a few guides available.
Now, no you won’t be possessed by demons, possession bears vastly different symptoms from the Flow State, you won’t suddenly start hating God, or have inexplicable hatred, or gain joy from other’s suffering, or anything demonic (if you do however then that’s a serious problem too).