>Makes you wonder why the USA hasn't built one?

They basically (almost) did. In 2013 ASML bought US Cymer(the maker of EUV light sources) and in 2001 ASML acquired the US-based lithography equipment manufacturer Silicon Valley Group (SVG) after it had encountered liquidity issues.

Basically, the US had everything needed, the EUV light sources and lithography machines, just spread over different companies facing financial issues, so ASML came at the right moment and bought them all and integrated into their own business.

Just because ASML is based in NL doesn't mean all of its EUV secret sauce IP is domestically Dutch. Most of it comes from the US, which is why the US government maintains such a high influence of ASML's trade restrictions.

"Most of [IP of ASML] comes from US" is an extremely generous sentence.

It is true those companies you referred to were bought and their IP has helped ASML in _EUV_, but they had 20 years of European IP before that, all related other parts of the lithography machine (and not EUV) that made ASML the company it is.

If you think that complexity is only in (light) source for EUV (is it already profitable for ASML, by the way?), then you have no idea the complexity of that machine!

Disclaimer: I worked in their metrology department.