I've recently found out (correct me if I'm wrong here), that 5nm lithograthy machines are made by ASML, which is independent and Intel invested in it. I've tried web searches but I still do not understand why Intel, for many years, "struggles" to go from 14nm to lower scales? I've found recent articles that claim "TSMC is to start making Intel's Core i3 on its 5nm process in 2H21 ". Why doesn't Intel just buy 5nm lithography from ASML and start to produce? I suspect processors' production need much more than wafer lithography, but do not want to make uninformed guesses as to the main reason behind Intel "problems".
I've read How are other chipmakers keeping up with TSMC if their processes are just the best? but have not seen answer to my question.