I think most of us do what we really want...we make choices all the time. Some will give up many things for a trip to a place they really want to visit.
Others, prefer to buy a house, car, whatever...
Often, over the years, a roundtrip ticket to Europe has been cheaper than a trip from here to New York. There are lots of bargains out there--there are tons of ways to travel on a budget, even with children.
I think cost is an issue, but it is the perception of cost, more than the reality--I used to travel to New York City a lot for work, and would stay for a few days to explore the city because I find it so fascinating...so many people back home would say to me, but it's so expensive! Not so--but I rented an apt, not an expensive hotel; shopped for food at the local grocery (which I found cheaper than the one back in Florida), stood in line for discount Broadway tickets, went to the museums on "free" days, etc., etc.
It all depends upon whether you want to be a traveler or a tourist...and there is a difference.
To each his/her own, but I know my life and the lives of my child and grandchildren and my friends and other family have been enriched by our travel to other places...and none us has ever been "wealthy" in terms of $$$.
International travel not only shows the traveler a different way of life, it changes the traveler in ways that are so important IMExperience. Living out of the country is even better.
Our country looks different seen through the eyes of a citizen who has seen other countries and gotten to know other people.