I am no expert, but I think one major reason was Trump. He was a supporter of the lab leak theory. Like many others, I was quick to dismiss anything Trump said, and I am not even American. Everything Trump said sounds like a conspiracy.

I also finds China's strong denying and uncooperativeness of finding out the virus origin is strange. People would not blame any country if the outbreak came from a natural origin, their reaction makes me think something is going on there.