Travel is a set of unique experiences that form unique memories. Part of what’s addicting and pleasurable is that it helps slow down the perception of the passage of time, among many other positives.
It’s also self reinforcing in that when you think back, you tend to disproportionately remember travel vs other experiences.
There’s clearly a lot more benefits than that, but it certainly seems like a significant factor.
When I travel, either I want people or I want solitude. Most of my enjoyment from traveling comes from seeing family and friends, and it really doesn't matter that much where we're situated. But if I have neither, then being in a sea of people is really worse than just being at home. In that case, I want to be alone, and I can easily get that by driving 1.5 hours into the mountains where I live.
Travel isn't a bad thing, in fact it can be a great thing. My problem is that we've made travel out to be a grandiose life achievement. In the near past and for millennia, humans spent most if not their entire lives in one place, and there's nothing wrong with that.
Put another way, some of my travel fantasies are pretty out there, I just know I'll never do them. Even if I had the cash and was willing to spend it, at that point the experience would never match the fantasy.