It's "cool to care" - if you like something, don't be afraid to keep liking and caring about it. With some interests (like theater here), there's external pressure to stop liking what you like, because your interest isn't "cool".
If you pursue what you like on your own, repeatedly, you sometimes find there's people with the same interests. You start to recognize each other. And traveling around the world to participate in the thing you like can have lots of value.
It's the last part, the seemingly ridiculous travel, that I think is a key part of Alex's story. There's something about the kind of people who would travel overseas to see a musical, repeatedly. They really care about what they like. That's an extreme dedication to the interest, and that's how you find people who are also extremely passionate and motivated about their interest, or maybe even just about the community that has arisen around that interest.
That's the part of Alex's story that landed for me. I feel I experienced something similar 15 years ago in my own niche interest, flying from Australia to see Eurovision (before Australia was part of the contest). I traveled alone, but found ~20 other Australians doing the same thing, and some of them attended every year. That shared interest & shared experience became decade+ friendships. And for us it evolved into getting backstage, meeting artists, running local nightclub events with Eurovision artists flown in from Europe to Australia, and somewhat accidentally creating a national fanclub community of hundreds of people.
Crazy ideas around niche interests can spiral and snowball, as you provide ways for the crazy kids to find each other. And that seems to be what's happened here with Operation Mincemeat.
Cool does mean detached and aloof and unpeturbed. And theater kids (and Eurovision fans) "unpeturbed"? Yeahhh... probably not.
But the original cool would not have fallen to peer pressure of what others think either. The Fonz is cool, but The Fonz absolutely cares about his friends too.