I agree that you can be bigoted and well travelled like certain members of my family, and open-minded and never leave the UK. I also agree that spending a week at an all-inclusive abroad is far less mind-expanding that spending a week exploring some corner of Britain.
We holiday in both the UK and abroad and I don't really see the difference, to be honest. Yes, DC experience different languages and cultures when abroad, which is great, but you can have an amazing adventure in the UK. You can climb mountains, go kayaking, visit ancient or modern cities, ride a steam train, see dolphins in the wild, go bird watching, sunbathe on a white sand beach, etc, all in this wonderful country. Similarly, you can travel 8000 miles and never leave your luxury hotel and see fuck all of the country you've sat on a plane for 12 hours to reach.
Travel and a sense of adventure are all you need and those can be provided here as well as there. Having said that, I love going abroad and we regularly take our DC abroad, but we love our holidays here in the UK just as much as the overseas ones and we have just as many adventures.