I have written elsewhere that reality exists as a spectrum of possible outcomes. What imagined fears and its corollary, illusions do is to add to the mix to affect possible outcomes. Imagined fears are internally generated by past wrong conclusions and illusions are externally generated to disguise reality. But in essence both does not exist.
In chess we know this. It's part of the arsenal of the mental warrior. My observation is that we are more aware of the illusions, the psychological attacks from external sources than we are of our imagined fears, our enemy from within.
But nevertheless many crucial games are lost because of these factors than from an objective evaluation of possibilities of positions. ie reality.
(As opposed to imagined fears and illusions ie. our perceptions).
I believe if we look there (particularly imagined fears), we will find the games, the extra points that will produce our champions, our first GM.