But that one would be current reality. People's tendency to click on things that outrage them (and therefore generate advertising) is one of the things that lead to social networks becoming echo chambers of various conspiracy theories. The result is sites like InfoWars, which helped make Donald Trump president. The war bit hasn't happened, but it well could.
My favorite book about this topic is _Trust Me, I'm Lying_. It lays out the human incentives that guarantee that the recommendation engines will produce terrible for us results.
Give it time.
"Lenat fed the massive Traveller rulebook into the system and asked it to find the best way of winning. Each night, after several hours of trial and error, Eurisko would spit out a few strategies—some interesting, some impractical, some ridiculous. At one point, Lenat remembers, it suggested he could win the game by changing the rules."
https://www.wired.com/2016/03/doug-lenat-artificial-intellig...
The authors commented that having a computer (when Pc's where ultra rare and expensive) would be useful :-)
I commented at that time that a PC was essential and working at the cutting edge of AI would be "useful"
Traveller (book3) was the basis for Elite as well
Also Eurisko and other symbolic/semantic systems are fundamentally different from the NNs popular today.
The scenario may work with a human actor/corporation working with the AI, but then it's no longer that cyberpunk (and could probably be done with a large enough grid today).
The latter already happens with the existing small replicating machines that we know. We usually call that cancer.
TLDR; The problem is chemistry not design.
Yea, that's not actually well supported. There is no where near enough coal for all wood over that time span.
Larger creatures like termites where probably missing. But, micro organisms don't eat dry wood on their own very quickly.
I wrote a whole blog post on this but tl;dr AI/ML can do unethical things without anybody knowing.
I guess the central point is that even if they aren't advanced enough to enact OP's scenario, they do not understand negative repercussions outside of their specific domain and so can unscrupulously cause havoc by proxy once they get smart enough.
Consider a model whose inputs are market prices, outputs are market transactions, and which has a naive value function that simply optimises for the amount of profit is trades result in in a relative short space of time. It's plausible that it could detect trading patterns that correspond to market crashes that can be exploited for profit.
These trading patterns might actually be causing or supporting political / economic shocks, such as bubbles, corrupt or unethical behaviour or inter-state conflict that then cause these crashes, but, to the model, this would be invisible or irrelevant. It would learn to perform trades that encourage these same shocks (e.g. undermining a large employer, causing job losses that cause political anger), and profit from the consequences. All without ever "understanding" what is happening outside of its model or having malevolent intent.