I have what I've found to be a good counter to lazy pseudo-credentialism: "So, you say I should defer to you because you 'work in health-care?' (To use your example.) "Yes." "Have you ever expressed opinions about teaching and how schools should be organised or how teachers should do their jobs?" "Yes?" (Because everyone has an opinion on schools, for the last 50 years.) "I have various degrees in didactics/pedagogy, economics, political science, sociology, linguistics, semantics/semiotics, the ideas of history/history of ideas and requisite sub-subjcts, and 25+ years of experience teaching all ages. What makes you qualified to have an opinion of teaching or on the subjects as such? Are you going to shut up about schools and teaching from now on?" --- That usually ends any discussion or casual credentialism-intended-as-a-gag. Teaching can of course be replaced with any subject or skill where your knowledge/credentials are greater than the opponents. Style and form to be adapted depending on context of course.