By that logic, you should probably stop programming altogether because all runtime of managed languages is written in C. What if it all comes crashing down?!
I do worry about it. I probably wouldn't gamble $100,000,000 on any program, if I had that money to start with, because I could never be 100% confident in a system being bug-free. But I can minimize the surface area of C that I expose, and use better tools where possible (which is often). Given that I still do need to write programs (even C is more reliable than doing things by hand), what other option is there?