Optimism and Pessimism are viewed very differently in different Countries (Germany vs USA) and even Regions (Silicon Valley vs idk Utah).

Apart from that I think the article is mostly wrong. To make progress you need agency and self-confidence. The effects of Optimism and Pessimism are very context-dependent.

Just one example: A very driven and confident pessimist might be much more motivated to find a solution for Climate Change, because he knows for sure otherwise Earth is Doomed.

While a very driven and confident optimist in Politics might reduce Carbon Tax, because he knows for sure that Technology Companies will find solutions for Climate Change and they'll find it faster if they have more money.