It's not approaching the abyss that's bad, it's how often you do it.
Over the last couple of years, we ran up to the edge (as a world) at least 3 or 4 times, and pulled back. The trouble is, that frequency is increasing and people are becoming jaded.
In 1962 we jumped to the edge, and everyone backed off very quickly. Now it's "ho hum, the edge again, let's buy on the downside".
If we assign a probability of going over of say 10%, then the cumulative probability of the worldwide crash leading to enormous war over the next couple of years becomes a near certainty, given the rate of increase in the frequency of potential crisis triggering events.
And, from what's being said, I have to suspect that computer trading is being set up to take the fall for causing panics.
Also, I'm well aware that there are plenty of smart people working for the Fed and the Treasury who are well aware we are close to worldwide panic and markets dropping past the bottom. They've got a lot of computers and a lot of tools, so the question becomes this, will they attempt to manage a controlled crash, and at least limit the damage? And if so, they'll never ever admit they did such a thing, because the idea of simply accepting that we've got it coming and they did the best they possibly could would be essentially buying the rope and building the gibbit for their own hanging.
But I do have to wonder, as if I was doing it, I'd rattle the market a few times to get as many retirees out as I could, and then let er' drop.
OFC, the other explanation is that the insta-trading "whip half a penny off every move" robots saw a chance to make money on the drop, so they shorted a ha'penny, sold, shorted, sold, and drove the market down by making money on the drop. Then they saw a rise, so they whipped off that ha'penny all the way back up. That's not a market, BTW, that's insanity codified into software.