Probably because the actions of those that have any power to change anything aren't exactly "optimistically determined". We have some of the most powerful men

Probably because the actions of those that have any power to change anything aren't exactly "optimistically determined". We have some of the most powerful men in the world attempting to start either another Cold War or at worst WW3. Existential challenges facing humanity aren't given the time of day compared to "hurrr durrr spy balloon!1!". Mass shootings go by and all anyone sees is some variation of "thoughts and prayers" yet nothing changes. When the people with the power show no willingness to improve a world which is on a downhill slope from the perspective of many young people I am not surprised that doomscrolling merely reflects reality back at you. Optimism needs to start with leaders that have the power to actually change things.