I learn things in my free time in order to beef up my skills for the next employer since the only way you can get a raise is to change jobs.
That should not be your only reason.
You should be learning for several reasons.
First, its' professional competence - if you ever join any professional organization, they all have mandates for continuing education. I.e., you must always be learning new things, if nothing else than to keep current. You cannot let your skills go stale - learn new things, technologies, and be educated enough to know what are fads, what are useful and what can be used the next time around.
Second, learning is fun. If you're interested in the topic, learn learn learn! Nothing's worse than the old fogey in the cube who refuses to learn anything and insists on using outdated technology and references because they refused to believe there may be something better.
Sure the old ways may be good, but how do you know they're still relevant good, or necessary? You learn new things, then you compare them. Some of them you quickly find out are flash in the pan stuff that dies out, others contain worthwhile concepts worth exploring. And maybe sometimes you learn something new that blows your mind away.
Finally, learn in order to simplify. Humans are lazy. Learning something that lets you be lazy is natural and beneficial - go beyond writing mere scripts, and learn how perhaps to automate things better.
And especially us technology workers where things move so fast, you need to continually learn new things in order to just keep current.