The debt problem in the United States was supposed to destroy the economy. Instead, the deficit is shrinking

Heh. Notice a subtle substitution here :-) The deficit might be shrinking, but the debt keeps on growing.

Also, Scott Adams' list looks like the list of hysterics that a variety of Nervous Nellies threw over the last half a century or so. Media loves declaring a impending disaster for obvious reasons. How many of them were actual slow-moving disasters coming?

Thanks. My claim is somewhat different, though. Adams says that "whenever humanity can see a slow-moving disaster coming, we find a way to avoid it". This is an all-things-considered claim. My claim is rather that sleepwalk bias is a pro-tanto consideration indicating that we're too pessimistic about future disasters (perhaps especially slow-moving ones). I'm not claiming that we never sleepwalk into a disaster. Indeed, there might be stronger countervailing considerations, which if true would mean that all things considered we are too optimistic about existential risk.

Thomas Malthus famously predicted that the world would run out of food as the population grew. Instead, humans improved their farming technology.

I feel that's a bad framing of the what Malthus said. He predicted the world would run out of food if the population grew without limit, which he said didn't have to happen, and has not in fact happened. The Wikipedia article presents a more nuanced view:

Malthus argued that two types of checks hold population within resource limits: positive checks, which raise the death rate; and preventive ones, which lower the birth rate. The positive checks include hunger, disease and war; the preventive checks, abortion, birth control, prostitution, postponement of marriage and celibacy.

If humans today kept having as much children as they biologically can, and if no other 'negative factor' constrained population size, then hunger eventually would. Our food production technology couldn't keep up if we literally filled all available space with humans; eventually there would be no space left to grow food.

When I was a kid, it was generally assumed that the world would be destroyed by a global nuclear war. The world has been close to nuclear disaster a few times, but so far we’ve avoided all-out nuclear war.

I don't think that "after decades of Cold War standoff and several very close brushes with a nuclear launch, the Soviet Union peacefully fell apart, greatly surprising everyone" counts as "we saw a disaster coming and found a way to avoid it".