They flood an industry with funds and let them all compete with each other. Then they back the biggest winner. A command economy usually mandates X units of Y good. This isn’t quite that.

I am talking about the economy in the Western model, it works well if there is competition. And it usually needs the state to do moonshots, like the literal moon shot or Silicon Valley. But the American economy was the most impressive during the Roosevelt years. The war production was insane, with 75% state planned, state built and state owned factories. The private sector was dominated by oligarchy owned monopolies, which means it wasn't impressive¹. The government had no time for conservative fairy tales and needed to take initiative.

What helped was the public outrage over the insane profits the American oligarchs reaped during WOI. This enabled Roosevelt during WOII to set a maximum profit margin for the oligarchy owned factories and fined those who evaded the law. It was a shock for the conservatives to see how the bureaucracy turned America's mediocre output around with a fast, efficient and lean production monster. The monopolists had to resort to propaganda, claiming the government's success as theirs, injecting the falsehoods we now all take for granted.

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1. As an exercise, think what would be possible if all the cash piles didn't sit at big tech, but instead enabled competition. Meta isn't still more than a useless addiction factory.