Long ago I had the pleasure of introducing a young friend to types of food he hadn’t tasted before. He was quite comfortable with his American style hot dog and hamburger meals and wasn’t certain he wanted to try new and strange dishes. People differ in this regard. Some are eager to try new cuisine, see new places, and encounter new people and cultures. Some are not. And some are even rather intimidated and reluctant to leave their familiar comfort zone. There is a lot to be said for the predictability of the familiar, perhaps similar to well-worn shoes.
After some gentle persuasion, my friend agreed to sample a few dishes. I reassured him that nothing would be forced on him and that he might even discover some exciting new tastes. If he found that he didn’t like a dish he would not have to finish it. But he would never know what he might be missing if he didn’t explore a bit. Once he started, however, it was hard to stop him. He was pleasantly surprised at how interesting and tasty some dishes were. He was particularly reluctant to try foie gras knowing it was goose liver, though he fell in love with it by the second bite.
As I noted earlier, people differ in their tastes for adventure. We might just leave it at that but for two reasons. The first is that being rich is more interesting and exciting than being poor. I am speaking here of experience rather than money. Seeing and engaging new and different places, meeting new and different people of different cultures, listening to new and different music can make life richer. The core of a liberal arts education (as opposed to acquiring professional skills) is the introduction to and broadening of our understanding and appreciation of ours and other cultures. It makes our lives richer.
The second is that openness to change is a necessary aspect of economic progress. Technical progress disrupts the established order but increases our productivity and standards of living. Global trade not only significantly increases our material standard of living but confronts us with other people and cultures as well. Both–technical progress and global trade often impose changes on us (such as the job skills demanded in the market) that we might otherwise not choose or want. If people can choose to live where their opportunities are greatest and if firms are able to employ people with the skills that best fit the firms needs, economies will be more efficient and will raise the standard of living for everyone. By allowing the disruption of innovation and trade we will have the opportunity to, or be forced to, confront and deal with strangers more often.
This can have a negative side for those who do not easily embrace adventure—those who prefer the familiar (hot dogs and hamburgers). If new neighbors come from different backgrounds and cultures, adventure lovers can enjoy the excitement of learning more about other places and people. But those uncomfortable with strangers can be – well – uncomfortable. Economic advances can also have negative impacts on those whose skills are no longer needed and we would be wise to develop and support government measures to soften and facilitate the needed adjustments.
A predisposition to seek and embrace adventures or to shun them is given to us by nature. However, civilization and its advance builds on nurturing more social skills and openness. Failure to teach/convince our fellow citizens of the rewards of adventure (or merely accepting and adjusting to change) can lead to disastrous results. In extreme cases unease can turn to fear/hate as in the recent white nationalist terrorist attack in El Paso by Patrick Crusius. As-his-environment-changed-suspect-in-el-paso-shooting-learned-to-hate. The nature of public debate on race relations, religious freedom, globalization, etc., and the words of role models can have a profound impact on how those confronting change formulate their views on these subjects.
The world is a better, richer place when all of its people respect one another and live peaceably together. We and our education systems (school, churches, clubs, jobs) should do our best to encourage those reluctant to welcome strangers of the positive experiences it can open to them. By learning to understand different ways of thinking and doing, we not only enrich our lives but can strengthen our own ways of doing things (our own cultures). Such interactions can show us what we like and value about our own ways and what we might adjust in light of the interesting practices of others. This is what the American melting pot is all about. It has produced a vibrant, dynamic and economically flourishing country. However, it is more friendly to the adventuresome types than to those resistant to change. We would do ourselves and our country a favor to kindly encourage those “left behind” to open up more to the wonders of our changing world. With regard to a difference subject of misinformation Anne Applebaum explores multiple approaches to this task: Italians-decided-to-fight-a-conspiracy-theory-heres-what-happened-next?
Warren's space 
See also David Brooks’s description of mass murderers as anti-pluralists.
Brooks doesn’t say however how to get the unum out of the pluribus.