I don't think you have any idea of how hard EUV was to pull off.
They toiled for 20 years without guarantee of success. They managed to pull it off and now they own the bleeding edge process and will do for the foreseeable future. If someone wants to do the same, they can become competitors.
It's not just a question of patents, they keep almost everything about these machines secret.
Back in 2005 the researchers who worked on EUV lensing (mirrors, really) were very cynical and thought that it would never pan out. Coffee breaks were hilarious. It ultimately took a whole lot of time indeed.
That is a bit of an oversimplification of what happened. A lot of basic research was done by US labs. But it took ASML almost 20 years to convert this research into a production ready system and nobody else succeeded. And they also got some big research grants from the EU[1]
The US had an EUV project that ran like 2-3 years and cost a few millions. ASML spent two decades and billions on it. That's like saying that the Manhattan project was given to the US by Lise Meitner and Otto Hahn.
They toiled for 20 years without guarantee of success. They managed to pull it off and now they own the bleeding edge process and will do for the foreseeable future. If someone wants to do the same, they can become competitors.
It's not just a question of patents, they keep almost everything about these machines secret.