In the present it is better to be optimistic than pessimistic. In short, you feel better about the future, hope brings more happiness than fear. And if everyone is optimistic, and acts as if the optimistic future will come about, it may help bring that reality, as in a self-fulfilling prophecy. The self-fulfilling prophecy rewards the optimist. They can claim credit for correctly predicting the future and live in that better future. The self-negating prophecy of the pessimist does not reward the pessimist, who had to be wrong to warn people off the wrong path. The pessimist may say:
“If you don’t get off that path, you will get run over by the trolley.”
They are warning
“Get off the path.”
“You will get run over by the trolley”.
Perhaps they got off the path so did not get run over by the trolley. Thus the pessimist was wrong. Alternatively, they did not get off the path, someone died, and people hate “I told you so”. People don’t like pessimists because Misery loves company.
However, if the future brings risks, and the optimist fails to prepare for those risks, (“She’ll be all right, mate”) bad outcomes occur that could have been averted by a more realistic or pessimistic take.
So perhaps we can think of a spectrum of reality-distortion:
In the absence of other information, the realist is best, having an accurate assessment of the risks and rewards of actions on future outcomes. But in a world that favours optimists, the accurate forecast faces the same problem as Cassandra, uttering the truth but not being believed. One may need to be more strongly negative to bring others to a realistic position, splitting the difference between optimism and pessimism. By expanding the Overton Window, pessimism is a palliative to excessive optimism, repositioning realism in the centre, and reminding everyone that outcomes are probabilistic, not guaranteed.
In short, we need a distribution of behaviours and ideas (an Ensemble) to enhance both individual and group survival. Individuals can and should specialise, it is how we make progress by going deep in selected areas, rather than wide across them all, yet schools, bureaucracies, and other institutions aim at homogenisation in skills, thoughts, and actions, as if we are all (at least those of us in schools) are to be as close to interchangeable parts as we can be made. Everyone is supposed to be slightly optimistic, extroverted, enthusiastic, and so on (but not too much!). Those who see the risks or downsides of whatever the hive mind has asserted is the proper course of action are dismissed, ostracised, or ignored.