Our culture already has the concept of hidden messages. You know those children's detective stories where the gang finds e.g. a book with some words highlighted for secret messages?
Or people playing pop songs backwards and claim to have found satanic messages? Or more generally the pop-fiction concept of finding ancient wisdom in old texts? It's a common trope everywhere. How exciting! Just ... that isn't reality for the most part. Except that it will totally be a thing.
People loose access to their Bitcoin. All the time.
Most Mining rewards from Bitcoin were early. And early on few people saw Bitcoin as a store of value. And it's exchange value wasn't that high. It is hard to estimate how much Bitcoin is lost forever. On some old laptops. From ordinary people that just wanted to buy some weed.
Here is a podcast episode about someone searching for the Bitcoin he had back in the day.
Maybe we should have distributed all mining rewards more slowly. Or maybe we shouldn't have and not knowing how much money actually is in supply is part of the design.
The future is going to be a mystical place
This concept of people finding Bitcoin will be everywhere. People finding Bitcoin - in paper wallets in a safe, with their grandma having highlighted 24 words in a random book in the shelf, with a steel plate hidden under the tile in the floor, with someone stumbling upon an 20 year old Reddit post of some idiot who wrote it down in public without anybody noticing.
(I think generally searching through ancient Internet stuff that takes forever to load is going to be a thing. Like the library of Alexandria. Be prepared for fun times.)
Remember, there are billions of people on this planet. All the stuff that can happen, will happen.
In real life you will hear about it because everyone knows someone who knows someone. In the news because it is an easy story to tell - comparable to people finding native american gold in their backyard - just that it can happen to anybody anytime not just new homeowners. In fiction novels because it is easy plot device. In Navy CIS like TV shows, in cinema, everywhere.
It will happen regardless of Bitcoins price
This is not a prediction that depends on the world being hyperbitcoinized and people finding a $5 note on the way home. No, the pieces are all in place right now. Low amounts from 2010 are a treasure now. And your normal life savings could be a treasure to your grandchildren.
And make sure to not loose your Bitcoin in an actual boating accident that somebody has to find in 100 years.