I didn't know this was happening. So I went to Google Maps and checked it out, and it is a huge project.

I understand how Dubai and similar places get to expand so quickly, but this does not make much sense for Egypt.

Looking at what is being built, it starts to look familiar: huge city sectors which are multiplied in layout and construction style, a massive "design part of city once and reuse multiple times" like it so often is happening in China.

https://www.google.com/search?q=china+egypt+new+capital then yields the answer.