system
Given the following post, respond as if you're commenting on Reddit:
human
[DC/Marvel] If magic is something that can be learned, why do non-magical characters never attempt to learn some magic?

Someone like Batman could sure use some magic, if not for fighting then at least for utility. Someone like Superman is aware of their weakness to magic but he doesn't choose to try and address it. 

I understand the Doylist answer (too boring if everyone uses magic) but is there a canon explanation?
gpt
I think the Doylist answer is key here, but for an in-universe reason, its likely because magic is HARD. Most casters in Marvel and DC either are immensely skilled or come from a genetic background that aids them in learning.

For the most part, we don't get to see the washouts, the hundred acolytes who, try as they might, can't cast a simple ward spell without blowing up their arm. Magic tends to be a "dot your i's and cross your t's" kind of deal and not everyone has the will or patience to be absolutely engaged in the process.

There is also a second issue in that magic isn't free, ever. There is always a cost associated with using magic, and few are capable of accepting the risks involved. This also bridges into the third reason, in that once you get into the magic world, YOU DON'T LEAVE. You become a nice fancy target to all the other magical creatures that tend to leave the normal reality alone. By entering their world, you are saying that you are willing to play the game on a different level, one that usually is far more dangerous and intense than most on the prime plane have to deal with.

Sure, Kal-El has tangled with gods and demons every now and then, but most don't tend to concern themselves with him. Now look at Constantine, who deals with apocalyptic monstrosities on a weekly basis; many who would scoff at such silly means of combat as "punching really hard"

In essence, magic is a dangerous game to play, and unless you're willing to accept the risks and rewards associated with bending reality, its best left to the experts.