All of us as humans have limited time, so we can only learn so many skills given the time we have. If you are spending a lot of time learning skills that aren't relevant to what you want to do , then you are building yourself up to be mediocre. Learning any particular skill is great IF you can find some way to apply it down the line. If you're going to into database administration or back-end web development, knowing SQL will be great.
I'm not trying to discourage anyone from learning SQL or any technology, but what I am saying is the majority of your time should be spent learning skills in the field you are trying to pursue. I'm pursuing web development, so I wouldn't be pursuing the same knowledge as someone working in other fields of IT. My time would be much better spent learning various web development technologies as opposed to learning the intricacies of routers, etc. Find what you want to do and become extremely competent in that is my opinion.
I'm not trying to discourage anyone from learning SQL or any technology, but what I am saying is the majority of your time should be spent learning skills in the field you are trying to pursue. I'm pursuing web development, so I wouldn't be pursuing the same knowledge as someone working in other fields of IT. My time would be much better spent learning various web development technologies as opposed to learning the intricacies of routers, etc. Find what you want to do and become extremely competent in that is my opinion.