Gandalf is not human. He's a demigod in the world of Lord of the Rings. A Maia.

So Gandalf is immortal. But what is Gandalf doing? He's making... Fireworks!

He can do magic a hundred times stronger and more impressive, he knows almost everything.

Yet (when the world is not in danger) he pleases the hobbits by making fireworks...

And that makes him happy.

And that's it.