I know this is probably too broad of a topic, but there are some great tools out there that allow one to use solutions created by experts, to build something new without actually possessing expert knowledge in that topic. Some examples are:
LLVM: you can build a programming language that compiles to LLVM IR — and get all the optimizations for free.
SAT solvers — convert your NP-hard problem to SAT and run a SAT solver on it.
Boehm(-Demers-Weiser) garbage collector — collect garbage without actually explicitly writing any garbage collecting logic.