Not the parent, but I believe he says he considers himself an expert of two languages, and reasonbly proficient in five, not that he's an expert of all of it.

Not the parent, but I believe he says he considers himself an expert of two languages, and reasonbly proficient in five, not that he's an expert of all of it. It's hard to know what people mean by expert without a defined benchmark of what an expert is. I would have previously considered myself an expert of one server side programming language, but actually I rarely read the C code, and never really cared about how the functions conformed to Big O notation; I have profilers and metrics and can worry about specifics as and when they present themselves as problems. I can bootstrap a linux system, docker, kubernetes, CI/CD, secret store, provide monitoring and metrics solutions, and have guided several such systems through fairly strenuous security conformance. I've also did delivered some front end JS work previously. Knowing more than one area definetly has benefits but it doesn't preclude you from delving deeper into one of the areas. Today I act as a consultant. I go big corps and teach them how modern dev works, and how to achieve this in a security concious and cost effective way. I get paid pretty well and I doubt I could do this if I was simply an expert in Java for example. Edit: We live in a where most devs over 25 expect to be "senior" and can actually achieve this because most orgs are unwilling to pay for experience. Personally, I wouldn't sweat the labels too much.