[jheriko]

There are some absolute, rather than relative measures that you can use to gauge your skill. For engineering fields (not just software) the 'toolmaker' analogy is a good one i find. Until you understand what involved in making the specialist tools you need for your field, and can actually make those tools yourself then you are far from mastery.

This is not entirely straightforward though - a bit of a rabbit hole you could say. e.g. should a programmer stop at the compiler? The CPU? The circuitry? Electronic components? The laws of nature? Tools are built with other tools after all and some tools are provided by nature...

On the other hand, if you haven't made even the first step towards understanding your tools then thats not really a problem to worry about.