As people in the US in the early 21st century get older, they become increasingly different from one another.
Walk into a preschool classroom and you'll notice how similar all the kids are. Any one of them can play with any other of them, regardless of gender, skin color, family wealth, family religion/politics etc. While they have the beginnings of distinct personalities, they do not yet know what specific things they like or dislike, have little or no personal baggage, have not yet learned to dislike whole categories of other people, do not understand religion beyond Santa Claus, have only the earliest understanding of gender roles, and have no political opinions.
By middle school, cliques have formed around gender, race, religion, fashion, and sports. The pool of people sufficiently like oneself to befriend might be a couple dozen in a school with hundreds of kids. The shared experiences of growing up together are still present, as is a shared fun-loving attitude, but the gaps between people have widened.
By adulthood, the divisive categories expand to include politics, socioeconomic status, career factors, entertainment preferences, preferences such as urban/rural lifestyles, hobbies, and so on. The pool of potential friends is spreadsheet-filtered down to virtually nobody. A Texas A&M fan cannot be friends with an Alabama Crimson Tide fan, even if neither went to those schools. A Ford truck guy can't help but look down upon a Chevy truck guy. The obese have obese friends, and the skinny have skinny friends. Vegans are not invited to their neighbors' barbecue. Pentecostals can't tolerate Episcopalians. Parties don't happen because everyone hates everyone else's favorite genre of music. Don't even mention politics.
Also, adults tend to blame everyone else for being too different from themselves. We see it as either foolish or morally wrong to be different than ourselves. Think through all the examples.
By retirement, most people are almost completely defined by the ideas and identities they have consumed in the past. The sole unifying factor for adults in modern American culture is that we can generally agree on the high value of desirable things like luxury vehicles, iphones, giant 5k televisions, big expensive houses, vacations, etc. Most also agree that high-paying jobs, no matter how meaningless or destructive, are better than low-paying jobs, no matter how important or constructive. Thus, consumerism/careerism is the last thread that most Americans have in common with one another. Consumerism funds media, and thus media comes to resemble propaganda promoting the consumerist/careerist promise to happiness and connection.
But consumerism/careerism also tears us apart, because there are so many niche products, services, and ideas that we each took a one-in-a-million path in our identity formation history, ending up in a place where we are extremely different than any of our peers, who themselves are radically different than anyone else. Compare modern life to life hundreds of years ago, when people had a lot more in common thanks to a lack of products, services, and ideas.
When we choose to live in a certain housing product, wear certain clothing products, listen to certain music products, watch certain TV or movie products, drive certain transportation products, eat certain food products, enjoy certain service products, subscribe to certain media, and adopt certain political views, we add layer after layer of difference between ourselves and others. As we become more and more different over time, we get out of touch with old friends with whom we previously had a lot in common, and felt a lot of loyalty toward.
Post-retirement life cannot resemble the carefree days of childhood friends and family connection because of who we became over time, and how different that is from everyone else. I suppose one could work toward shedding as many layers as possible, in an attempt to have more in common with other people and to resemble a child again in our attitudes and willingness to connect. One could divest themself of most material possessions, drop their beliefs about religion or politics, open their mind to the appeal of previously despised aesthetics, and to appreciate others for the innocent games and giggles they can enjoy together rather than what the other person could do for us professionally or sexually.
However, this is all easier said than done. We intuitively resist the loss of our identities and deepest values/beliefs. We cannot forget the things which make us fearful or inspired. We have a hard time choosing to consume almost nothing when we've devoted our whole lives toward consuming more, or else we'd have to view our past as a waste. It is extremely hard to become indifferent to politics, religion, aesthetics, race, gender, wealth, luxury, or the things which aggravate us. Plus, we cannot divest ourselves of sexual urges, the aches and pains of old age, or our less-plastic neurology. There is no way to again become as equal, as open, or as energetic as the preschoolers.
Yet the cultural status quo is the path to decades of bitterness and loneliness as a retiree - too different from anyone else to have anything in common, or too focused on the trappings of consumption to care about anyone else. This is how so many people end up during the last decades of their lives, tragically trying to fill the void with things they shop for or screens they watch. While it may be impossible to shed all the insulating layers of difference with others, perhaps it is a worthwhile pursuit anyway. The catch is finding other people willing to do the same.