Some years ago I developed a mathematical argument for optimism:

Starting with the present moment and assuming endless future time, one can plot a measure of "total good." This total good takes into account our attitudes and how we react to things and is thus dependent on memory of past good and bad. For example, after a long period of bad, even a tiny moment of good can have more total good than an extended period of good greater by any normal measure.

This total good will go up and down apparently randomly. Given an infinite amount of time, eventually, by chance, there will be a spike of good greater than all previous good. Everything that came before this spike will be part of the story of causality of how this good was achieved. Since it is a measure of total good, it will mean that no matter what happened before, it was all worth it.

Of course, the same argument can be used to prove that things are getting worse. Eventually, statistics predicts a dip deeper than any before it. The trick is to look at the time from peak to next higher peak as a series of stories - like episodes of a tv show - each one starting with a challenge and ending in resolution of some kind. Think of the dips as just part of the story on the way to the end. Good can win in the end if you decide when the "end" is.