For me it's not so much about the process of learning itself. To be honest, I'd rather avoid having to learn how a tool works to use it. Software that prioritizes ease of use and friendliness has a much broader appeal—and, consequently, user base—than those that don't. There's value in that.
I chose to learn Vim, Emacs and other tools with a steep learning curve primarily because of their return on investment. They have great extensibility, so I can customize them exactly to my liking. I know that they won't radically change, or worse, disappear in a few years, as a lot of software does. So taking the time to learn how to use them is purely a selfish endeavor. I even put up with their quirks and shortcomings because of this, even though there might be alternatives that do feature X better, are faster, etc. Using these tools simply minimizes the chances I'll have to re-learn something else every few years. I'd rather avoid that.
I chose to learn Vim, Emacs and other tools with a steep learning curve primarily because of their return on investment. They have great extensibility, so I can customize them exactly to my liking. I know that they won't radically change, or worse, disappear in a few years, as a lot of software does. So taking the time to learn how to use them is purely a selfish endeavor. I even put up with their quirks and shortcomings because of this, even though there might be alternatives that do feature X better, are faster, etc. Using these tools simply minimizes the chances I'll have to re-learn something else every few years. I'd rather avoid that.