That can be a valid specialization, but the bar is higher than most people realize. If you're going to be a specialist in software development, it isn't enough

That can be a valid specialization, but the bar is higher than most people realize. If you're going to be a specialist in software development, it isn't enough to merely work at a company or three and advance through the ranks. You have to become so skilled at the process of software creation that your knowledge is recognized as universally relevant. You have to be in the top percentile(s) of people who do what you do. It's the difference between being a middle manager at a tech company and being, say, Rob Pike or Jeff Dean. (Maybe that bar is set a bit too high, but hopefully you get the idea.)