...would you still do it?
It seems like a fine test to me of the worth of things.
There's many activities we'd do if we couldn't show them off. People would do mathematics, for both the pure beauty of it and for the insight it lends to the world. People would do engineering for, again, the pleasure of invention as well as the practical benefit, even if no-one could see the finished works but the creator.
I think -- I know -- people would still study history. Again, it has its own rhythms and pleasures to it, and it helps the world make sense.
People would still look to learn, true learning that is, of almost any stripe or form.