I also started digging into this as part of a depression journey. One of the things that persistent pessimism also leads to is the concept of “learned helpless

I also started digging into this as part of a depression journey. One of the things that persistent pessimism also leads to is the concept of “learned helplessness”, which could be described as a kind of pathological pessimism. A state where on top of thinking certain outcomes aren’t possible, the impulse to try moving out of our current situation never even occurs. The equivalent of drowning in 2 feet of water, because it never occurred to the person to stand up. I’m also really grateful to have started moving away from this mindset. I wouldn’t say I’ve fully escaped, but I’m on the path. That book also provides some helpful reframing exercises that when applied consistently, start to re-wire default responses to situations. This has been transformative in my life. I think that the 90/10 split is an interesting way to look at this, and I tend to agree. I think the degree of optimism applied probably needs to scale inversely to the calculable risk (e.g. building an airplane necessitates lower risk tolerance). But in most situations, it seems like a much better default. And ideally this is always contextual to the situation at hand.