Ask HN: What if WannaCry would have tried issuing fake Bitcoins?

Not a whole lot. The fastest CPUs will net you less than 100 MH/s [0]. The fastest single-card GPU configurations will net you around 1,000 MH/s [0]. The current total hash rate is around 5,000,000,000,000 MH/s [1]. WannaCry affected around 300,000 PCs [2]. So if every WannaCry miner was operating off CPU and getting 100 MH/s, it would only be 30,000,000 MH/s. Or 0.0006% of the current total hash rate. If they all had high-end GPUs getting them 1,000 MH/s then that would bring it up to 300,000,000 MH/s. Or 0.006% of the current total hash rate. So WannaCry wouldn't even be a drop in the bucket. If you're wondering how the hash rate is so high, it's because mining has switched to using ASICs, the fastest of which run around 14,000,000 MH/s [3].

[0] https://en.bitcoin.it/wiki/Non-specialized_hardware_comparis...

[1] https://blockchain.info/charts/hash-rate

[2] https://en.wikipedia.org/wiki/WannaCry_ransomware_attack

[3] https://en.bitcoin.it/wiki/Mining_hardware_comparison

If I understand the OP correctly, he means could the blockchain be attacked by a vast number of infected hosts, causing a malware-induced change in the consensus of nodes, allowing BTC to be illicitly acquired, spent, or produced.

I believe controlling a massive number of nodes in the network via infection techniques like WannaCry used would open the door for many actual and hypothetical attacks. Please see the Bitcoin Wiki page titled Weaknesses [1] for more details about attacks involving the control of network resources.

More realistically, a simpler attack would be to go for control of the wallets if you have that kind of access to the infected hosts. However, if an actor had an interest in devaluing Bitcoin, to buy after a crash and sell after recovery perhaps, or just destabilize users' trust and destroy it (states?) then there could be a lot of profit in it I believe. Bitcoin has many competitors and enemies, is this something we should worry about?

[1] https://en.bitcoin.it/wiki/Weaknesses

Can you clarify?

There's no such thing as fake Bitcoins.