I'm not sure about that, most modern travel seems to be just another form of consumerism.
Only few are genuinely interested in the world around them.
Of course we will need some data to support my point :-)
How do you know? The benefits of travel don't come instantly like some binary "travel" door you walk through. Travel sculpts your character over time in small ways and small interactions. And why would it need to be an active self-improvement process? On of the beauties of travel is how passive the a-ha moments are, you just have to pull the trigger to go in the first place which many people cannot even do beyond a "someday I'll go" dream they carry to their grave.
Does hundreds of years of travel writing and tens of thousands of biographies of people who travelled before going on to do amazing things count?
So I guess here is your answer.
What I simply meant is that travelling for most people is just a form of leisure not a life enhancing experience.