Frankly, I feel that the shock comes from the fact that everyone was expecting the price to rise after the news of the ETF getting approval, or that the price would collapse if that approval was not obtained, but what happened is that the approval was obtained, and yet the price did not rise.
It makes true the statement used a lot that bitcoin remains very unpredictable. It may not perform as expected with a new development but may perform unexpectedly with a development that you could not expect or predict too.