Uhm. "Not giving a damn" doesn't cause depression I think. It's kinda the other way around? You know, caring too much and whatnot, or caring about things you can't change in a way as if you could.
Personally, I find the heat death of the universe comforting. That is, considering human society as it is now: no matter what, there will be no boot stamping on a human face forever. Those who "become one with the dust" cannot loose, those into accumulation of power and posessions can't win. That's kinda neat, after all, like a fail-safe. It's also the only real solid argument for things like compassion and irony I know.
You are here because thousands of generations of humans have found ways to cope and carry on and make today into a better tomorrow.
You could also say I'm here because hunger feels bad and fucking feels good. "Better tomorrow" sounds so self-righteous, and while maybe people in the past were that high-minded, I'm currently not seeing it. The US can't even close Gitmo because the people they abducted and tortured might take it out on them, wtf? We still live in the stone age in so many ways, and that's the supposedly advanced west. A few years ago in Germany, a girl was raped in the inner city of a small town while people just walked by. And so on. It could be argued that even one look at a flower justifies all suffering in the world, but it could also be argued that just one kid dying in terror and pain does not justify existence of life on the planet. It really depends on the mood, and for me on wether I had breakfast yet.
Remember when TV was thought to bring culture and information to people? Hah, me neither, but I take it there was a time when you could express such hope with a straight face. Then came the internet... yet the way 99% of the people talk on the web would get one hellbanned within 5 posts here. For every person with a book I see, I see 20 with their dumbification phone out. In the economy we consider shifting money to those who least deserve, but most desperately want it, as making money and admirable, and watch helplessly as our media, our food, just about fucking everything gets more and more consolidated into fewer and fewer trees of corporations and the corporations they own. All most people care about is what they need to do to get along, they just accept everything as given and go from there.
And yeah, then there's the people dreaming of actual immortality in all this mess. Just look at them. They've been creeping me out since I was a kid, not once have I seen a scientist talk about this who seemed to be a balanced human being.
Anyway, as Kafka wrote in his notebook, "Believing in progress does not mean believing that any progress has yet been made." But then again he also wrote this: "You can hold yourself back from the sufferings of the world, that is something you are free to do and it accords with your nature, but perhaps this very holding back is the one suffering you could avoid."
But that's not what you're talking about, children dying in Africa, is it? Or people who just want to feel like they have some agency in their life playing Farmville? No, the universe is oh so exiting, it's an awesome ride... bleh. Don't get me wrong, I sometimes still stare at clouds or my hand or whatever and am simply amazed. But a sense of wonder is only one part of the story, the other part is human society, which is nowhere near the awesome complex miracle the universe is, but often rather banal, predictable, suicidal on good days and murderous on bad ones, with ads everywhere, just in case someone has an actual thought in a quiet minute.
I still agree that one should not give up, if that can be avoided. But I disagree that "if they figured out a way to give a damn, you can, too." -- so many people didn't figure anything out (how many natives are basically dying from depression in reservations?), and if they couldn't, why should I be able to? We live on a planet where Stalin and Hitler and Mao actually happened, where the US is actually a thing, and where there is no reason to believe power, control and deception will not be absolute and insubvertible one day -- until the heat death of the universe, that is.
People who don't give up do that for themselves; they don't don't owe it to anyone. Maybe to the people who love them, maybe to themselves, but not to any old random schmuck of the past. I think there is no logical argument you could make for why people "have" to be happy and not just mope or become criminals, and hugs are really as good as it gets.