Aaaaah mysteries mysteries mysteries, where are you.
We're a race of explorer, we're like ants, we need new grounds to go feel lost and trace a novel path. But earth is small, and the mysteries of the universe get pushed further out of reach from the non specialists, and more ground is mapped in all domains. So, we artificially build new reachable mysteries. Our neighbors are part of a vast conspiracy to investigate adventurously. Our fictions and our gamesprovide additional universes to explore. We erase scientific findings to replace them with armchair pseudoscience which only benefit is to give us profanes an active role in research. We "do your own !", with the implicit hope of reaching our own novel findings instead of treading used paths. And thankfully, in a way, we're still facing this confusing death. We need room, that is, un-mapped parts of the room.
But without cheating, that is without us cheating, we used to be presented common sense mysteries which did bring a bit of oxygen in our shrinking world. We used to know much less, and speculate more. More importantly, we used to see less, less farther, less often. UFOs and Nessie need rare and blurry cameras (electronic/optical artefacts don't compensate for the real mysterious material shapes that used to be "captured" on film). Secrets valleys and undiscovered lands don't survive satellites. Our destroyed, disarmed forests hide no more witches or elves. No more tomb majestic, mysterious and exotic enough to curse their archeologists.
But possibly worse than all that, a recurring childhood nostalgia, triggering these considerations over and over again... No more Bermuda Triangle. It hasn't even been solved materially, we haven't found the flying saucer, magic portal, cunning pirates or angry kraken lurking in it, and hey, I'd even take that methane bubbles explanation... but it's even worse. It's statistically debunked, we don't hear about it anymore because... it does not "happen". It's neither an avoided cursed place, not an ongoing source of mysterious disappearances. It's not even a joke anymore, it's left the cultural landscape. It ceased to be a thing. No one care. Like in a child's room, corner shadow in which we could play pretend seeing it has been lit, not even on purpose, and there's nothing to see or speculate about.
Yay knowledge. Progress. But.. ignorance is so romantic. The sleep of reason produces monsters, but these monsters had something marvellous and poetic to them, that the current ones (be them real ones, or political conspiracy fantasies) will forever lack.