Nice find!
I kind of wonder if silver dimes and quarters still end up in circulation because somebody accidentally (or maybe out of desperation) spent them. Accidents can happen. Maybe a child grabs some change from their parents' nightstand, not realizing the jar was for silver coins set aside, and spends them on candy. Or maybe somebody like yourself was going through a big collection of old change (like REALLY old), and didn't notice the silver when they rolled them up or spent them. But all in all, silver is indeed very rare in our currency nowadays! Imagine a child getting a silver coin as change, and asking the question "why was our money once made from precious metals?" If there are still curious children in the world, a silver coin might spark an awakening. I know that I'm much wiser for having studied precious metals, the history of money, and so on.
EDIT to say that I remember helping my grandmother clean out some old drawers and cabinets before she died in 2016. We found some old cough drop tins filled with coins. We also found an old piggy bank that had been raided at some point, but wasn't completely barren. We didn't find anything older than the early 70s! Much of the coins were from the 50s and 60s, a few even older. It was pretty much just as somebody had left it, at least a generation ago. She told me to keep it all, so I added it to my collection of copper and nickel. It's heavy when time comes to move house, but I'm happy to have it. In the piggy bank was also a really old $2 bill (we switched to $2 coins in 1996) from the 60s. To her it was nothing, maybe ten bucks in loose change. To me it seemed like a treasure trove, haha! All that history, and lots of copper, nickel, and a bit of silver :)