It's partially negativity bias, and partially the effects of being in a low trust society. Some people may say that we still have it good compared to any other

It's partially negativity bias, and partially the effects of being in a low trust society. Some people may say that we still have it good compared to any other time in history, but humans tend to react more towards rate of change than we want to admit. We can "feel" when things overall are starting to look up or look down, and the last few years especially definitely have a lot of "look down" effects on us. You may try to kick things out when it gets too negative, but at some point all your friends may become negative. And then what? Do you kick yourself out of society, or do we recognize that there's systematic issues going on (a perhaps, as you say, "depression")?