There seems to be a trend of people declaring on the profiles what shade of #doomerism / #optimism they feel attached to. A sign of our times I suppose.
My sense is that this more an emotional / character aspect than any purely rational argument.
But I am justifying my own (mostly) optimistic stance by stealing Pascal's timeless argument:
Even under the assumption that there is no hope, the potential benefits of thinking there *is* hope are so vast as to make betting on it rational.