Please pardon my ignorance, I really interested in this. What kind of job where you are writing compilers for living? The one that I know is something along Mozilla's, Google's, Apple's dev that working on the Rust/Go/Swift language. Is there any other kind of jobs that also in this writing compiler for living category?
Those creating specialist processing chips more dynamically in FPGAs may also have someone working in that area if they intend to control the result via a higher level language.
Plenty of companies can have internal languages which need to be compiled. One would be Facebook with hack but in a normal company it isn’t totally improbable to go from “we need to configure some rules” to “we need to add more features to our rule language” to “we need to run our rules faster” to “oops we are now making a compiler.” And there are specialised consultancies to help with these compilers.
However I think GP was really alluding to working on programs that aren’t really anything to do with databases rather than writing compilers specifically