What helps me a bit is to think about what the world would look like in the years after a widespread societal collapse. Many of the things we rely on and take for granted today would no longer be available, so we'd have to do a lot of rebuilding of societal systems
But the crucial part is that if humanity ends up in that scenario, then the last thing we should do is try to rebuild society to be as it was before. After all, our current system is what is currently wrecking the world. That means we need to do what we can to proactively consider (and where relevant, implement) systems designed for a better world.
In all likelihood, I won't be one of the people who would be rebuilding in that scenario (chronic health stuff means I'd be dead before I got to that point), but there's still power in building new stuff. My hope is that if(/when) everything blows up, then maybe the things that I have helped build will end up as useful pieces for the people who come after to salvage.
Technofascists can hide away in their bunkers and network states when everything blows up, because I earnestly believe that the rest of us will stand a far better chance at surviving, even if we have far fewer resources than the billionaires. They fundamentally do not understand humanity, so all their silly plans for their "afterwards" are even more doomed to failure than our current, groaning structures.
No matter what happens in the coming years, there will always be an "afterwards". Time will keep ticking forward no matter what. I reckon that even in the super bad outcomes, humanity will continue to exist in some form, even if in drastically diminished numbers. However, I don't know that for certain. In the end, it doesn't really matter, because I'll never know what comes after me. If humans do end up being eradicated, then I suppose nothing I do matters. However, because I can't know if that will be the case, all I can do is operate under the assumption that humans will continue to exist when I no longer do. Consequently, I feel that my ethical duty is to do everything I possibly can to give those hypothetical people the opportunity to salvage some useful tools and building blocks from the wreckage of our collapsed society.
The neat thing is that this work is still useful in a world where things don't collapse disastrously. The question of "what would we need to thrive?" will be just as relevant in the event that we are able to avert a full on societal collapse. I find it useful to look back on the history that my life is built upon; whilst there's so much awful stuff that has direct throughlines to the awful problems we face today, there are also so many powerful acts of resistance and activism that help me build a template for what I feel we should strive for today. I imagine that the people who come after me will look back on us in a similar way. All I can strive for is to build little pockets of goodness that will help them in the same way that I draw strength of historical resistance.
Maybe it won't be enough, but that's okay, because I don't need to ask the question of "how much is enough?", because that's not answerable now, or ever. Thus I am forced to set that dread aside and just focus on what I can do to help.