Sometimes the keenest insights get their start from simple questions.
On a recent vacation that included a trip to Mexico, my niece asked me straight out, "Why do you like to travel?"
My answer didn't seem adequate because it rehashed all the usual reasons; to seek change, to experience new things, etc.
There's this thing that happens to me every time I feel I haven't answered a question adequately. Maybe it happens to you too. I spend time later trying to answer it better. It gnaws at me until I come up with a different formulation. And it's probably the reason why I pick up so many books on philosophy, history, and economics. All in the service of finding a response that is better, or at least one that's adequate.
After further consideration, this would be my answer.
I like to travel because it is more of a game than a puzzle. Puzzles have a preset outcome where the task is piecing the thing together the way it was originally constructed. Both the rules and the end result are already determined and the fun is found in discovering them.
Some things about travel are puzzles; airports, room arrangements, unfamiliar languages. But the real joy of travel is found in the open-ended experiences that come from playing the game. A really good game is one that has a simple set of rules—which create a complexity of possible scenarios full of interaction and surprise. So, once the basic puzzles of travel are solved the game can begin. And the rules couldn't be simpler; put yourself somewhere new, open up to adventure and always be ready to choose a different way.
This can mean simply leaving your guidebook behind and asking a local where to find the best breakfast. Or, if you're used to eating out frugally it can mean splurging on a meal that's crazy expensive (or vice-versa). It can mean traveling with a tour, or without one if you're unused to moving about unguided. It absolutely means being open to changes in plans and living with the reality that not all of your plans are going to happen.
Beyond the puzzle and the game, travel is a fear killer. Not caution; fear. Travel is the great denier that fear needs to be the guardian of our lives. Getting past the apprehensions of travel (and that can happen at the point of getting the plane off the ground, or when you spill out with wide-eyed wonder onto some city street in a country you've only read about), that's the thing that always kicks off some kind of endorphine party in my brain as I relax, smile to myself, and realize two simple things; those apprehensions were inflated, and...I'm traveling again.