Most crypto projects these days (and even Bitcoin, actually) are based on some kind of virtual machine. For example here's the first Google hit for "ethereum bytecode":

https://ethervm.io/

But writing smart contracts and whatnot directly in bytecode sucks; so, you make a compiler so you can write them in an (invented) higher-level language. For which you might as well hire a "compiler engineer" as any other kind. :)