[tsm212]

But the CLR is written c, c++ and assembly which is what runs c#. Also the syscalls that run down the chain are also written in c, c++ etc.

[struant]

That is just the runtime. That is smaller of fraction of what is going on when your programs execute than you think.

The C# code you write (and majority of the your code's dependencies) are JIT compiled to native machine code (or more recently there are AOT compilation options).