So?
If the workers have a 25 hour week with universal health care and great pensions who cares if the billionaires have spaceships to Mars?
Considering we are speaking about the US, those safety nets would come from the massive Imperialism the US commits constantly. Workers in the Global South would continue to slave away so workers in the US can live cushy lives.
In a Socialist system, we can end that, but under Capitalism there is no path to deliberately end the practice of Imperialism, as it forms the basis of US foreign policy, and why the US Empire has hundreds of millitary bases around the world.
Or we could be doing asteroid mining and getting raw materials from off-planet.
Marx and Lenin never wrote about that because they both died a century ago.
because they both died a century ago.
The idea of replacing all on world mining with magic sci-fi technology is exactly as implausible now as it was a century ago.
And we would continue to centralize and give power to fewer and fewer hands, when we could provide much better living standards for all.