This reminds me of the day I disabled Youtube history, suggestions, etc: I sometimes listen in Youtube to old civil war-era songs from my country, Spain (my great uncle was a partisan who fought against the fascists). Once I left the autoplay engaged and returned to my Youtube feed filled with current neonazi/extreme-right/conspiracy recommendations.

Retracing the browser history, it went something like: historic recordings of civil war/partisan songs -> later recordings by popular musicians of the most vanilla/famous ones -> current renditions of the old songs by extremist groups -> crazy political propaganda from those extremist groups.

As you say, it was a first hand experience of what unsupervised, mindless optimization looks like. Ethics are not factored in the merit function, so they just don't exist for the machine.