Optimism and pessimism are both two sides of the same coin.

Its basically an example of circular reasoning.

You assume a certain outcome, or something about certain outcome. You assume something is gonna be ‘good’ or ‘bad’. something is gonna go ‘well’ or ‘unwell’.

There is no well and unwell. Its just a label. There is only WHAT IS. And that’s the realistic chance of certain occurrence.

All but the estimation of that chance, is your own labeling, according to what is pleasing for you to imagine.

Some are prone to idealising. Others are prone to catastrophizing. Both are trying to extend their control over certain random outcome. Both are instances of wishful thinking.