Measles were also much more lethal and more infectious. It took a long time for the vaccine to be developed. Why weren’t people freaked out about the measles? For one, people knew way more about the measles. A new pathogen we don’t know much about is worse from a psychological perspective.
It also doesn’t really matter whether the old flu kills more than Wuhan. When a bank run is ongoing you don’t just stand there telling people theories. You take actions that give people the confidence that things are being taken care of. China, Hong Kong, Singapore and Korea did that. They took things seriously and applied decisive, sometimes even overly draconian measures. But that gave people confidence. Life goes back to normal there now. Versus here people just dilly dally and waste valuable time. We need to frontrun the situation.