Volume +
The second reason is technology choice. As explained by Gavin Baker in his blog, when Intel developed the 10nm node, it chose to continue to rely heavily on multi patterning using deep ultraviolet (DUV). This turned out to be a mistake. The implementation challenges associated with applying this approach on 10nm delayed Intel's launch by 4 years. Meanwhile, TSMC decided to go with EUV, which ended up being the correct approach.
https://vestedfinance.com/in/blog/the-empires-that-tsmc-built/
_- Steve