Actually this is false. It is possible to write a language that is both safe* and compiles itself.
If you're not up to that then fine, but please spare us the poor workman blaming his tools excuse
I can cut a straight line with a circular saw without using a guide or a guard, but I can do it a hell of a lot quicker with a guide to rest against and a guard to keep me from having to constantly check my fingers and chords etc. These things weren't invented because of bad workman, but because they make good workman better. Not everyone who notices that there may be better tools out there than C for the very things that C is used for is a workman blaming his tools.
Someone eventually needs to write the rules for translating the higher level language down to lower levels, but this isn't the same as "getting their hands dirty down to the metal" in the same way that you've implied because it can be done in tiny self-contained, small chunks following yet more rules and rigorously like a mathematical proof and therefore not be subject to the same pitfalls as languages like C. It also only has to be done once (per processor) but then the safety is ongoing.
This layering is just modular design and separation of concern. Look at IR in the LLVM project which has allowed an explosion of languages that can enjoy most of the same compiler optimizations that the C family enjoy using this principle.
(btw, the Rust project is very interesting in this subject)
* Of course, the term "safe" has a limited meaning. A compiler can't read your mind but, to the extent that a language is well designed, it can prevent you from doing things that you could not have intended to do and force you to follow rules that will never allow certain common errors that result from people having limited memory.