It would be suicidal for the owning class to let the working class starve to death. The 99.9% will kill to not starve to death and the owners are outnumbered 1000:1. They know they'd have no hope of survival. The military and police would turn on their masters to not let their friends and extended family die.

Besides, ruling over a nation of corpses isn't satisfying. There's nobody to feel superior to.

Capitalism requires consumption. Without it, nobody can sell anything and the corporations die with the citizens.

If we get to a point where human labor has no economic value, there will be a new way of redistributing wealth that takes the place of wages.

I'm not that worried about a future where human labor still has some value but not much and the kind of valuable labor is stuff every human can easily do. The ruling class would still want to incentivize working by not providing UBI but everyone would be working minimum wage jobs with a permanent high unemployment rate with very limited safety nets. That's a future of grinding misery but it wouldn't be bad enough to cause a revolutions, like mass starvation would. That's the dystopia that worries me.