it's the same with stock price. say there's a giant correction. the value disappears. it wasn't stolen from anyone. the same way the global economy has grown over thousands of years, and people are much wealthier - that isn't because they stole from anyone but the total value of the entire economy grew and "everyone" became wealthier.
Hmm I think I understand. It's hard to wrap my head around though: I gained socks (and didn't loose money), the sock maker gained money but lost time and resources, but nobody's money was stolen.