If you want to be a Python specialist, for example, working at a job where you do exclusively Python and you get paid more and more as you gain expertise, then your time is probably better spent learning Python and not branching out.
If you're more of a "full-stack" developer, you might continue to learn new languages and paradigms, understanding the underlying concepts but maybe never learning language-specific fringe cases. Someone who does this might enjoy learning, and might prefer to switch things up and change jobs every few years.
If you want to start your own company, you'll probably want to be even more of a generalist, not focusing on development entirely. You might have a bit of a specialty in one area (software development or sales), but you'll want to know enough about all areas of running a business to be able to understand what's going on -- but you might want to hire the experts to know and learn more about any one of the areas than you do.
If you want to be a Python specialist, for example, working at a job where you do exclusively Python and you get paid more and more as you gain expertise, then your time is probably better spent learning Python and not branching out.
If you're more of a "full-stack" developer, you might continue to learn new languages and paradigms, understanding the underlying concepts but maybe never learning language-specific fringe cases. Someone who does this might enjoy learning, and might prefer to switch things up and change jobs every few years.
If you want to start your own company, you'll probably want to be even more of a generalist, not focusing on development entirely. You might have a bit of a specialty in one area (software development or sales), but you'll want to know enough about all areas of running a business to be able to understand what's going on -- but you might want to hire the experts to know and learn more about any one of the areas than you do.