Learning is of course awesome. It's the entire point of life. We are all here to learn.
But, excessively doing things solely for the sake of "learning" is actually doing a disservice to yourself. You should do things with tangible applications to real people besides yourself, too.
There are a lot of preliminary or experimental avenues to explore, but once you find a handful with promise, my advice would be to try to follow those more deeply and apply the principles you learned to something with direct applicability.
What you'll find is that by turning an experiment into a product, you've actually learned a lot more than you ever thought that little idea could yield up. You'll gain not only depth but also breadth as you explore the implications of that product in various fields, gauge peers' reactions to the product and marketing, and attempt to develop your idea into a repeatable, profitable boon.
Tinkering is really important for a lot of reasons, but endless, exclusive tinkering results in a very superficial knowledgebase. I recommend that everyone follow several of their promises tinkers down the rabbit hole and see what comes out of it. I recognize that this takes effort and commitment, but I think you'll often be surprised at the results.