> it doesn't make sense for anyone to build a second machine.

Maybe it doesn't make sense for private parties, since it clearly makes sense for nations to not rely of adversaries for their supply chains.

I would also argue that it your ability to rely on a competitor that is critical to your supply chain depends on which laws that prevent anti-competive practices are present in the relevant jurisdictions.

This doesn't make rational sense.

Investments aren't financed by customers, they're financed by investors.

I reckon in today's money-printing world it's easy to get even $1bn if you can credibly say to the investors that you can charge each customer 90% of the full investment (hell, even for 10% it's still a great business!)

In certain cases the requisite machine required can inherently run at a capacity larger than the market would ever require. In the case of new competition the response of the monopoly holder would be to simply discount prices by X% for N years until the new entrant goes bankrupt. In the case of presses, as the Capex was paid ~70 years ago by the incumbent they have an intrinsic financial advantage against an upstart.

It's a bad deal for investors to race to the bottom with an existing market player in a commodity business. It only makes financial sense for customers who dislike the marginal rate or feel there is a security need requiring their own supply chain.

The only way to break out of this would be a technical invention which allowed lower capacity production or technical innovation obviating the need for the monopoly. In the case of an industrial press this is a less likely outcome due to the physics of the machine and the intended application.