If you need reminding, sensible opinion was that masks didn't work. If you need reminding, sensible opinion was that a lab leak was impossible. If you need reminding, sensible opinion was that a vaccine wouldn't come for years. On and on.
Sense is inherently subjective. You are subject to the same flaws of logic and reasoning as anyone else. People believe that everyone else is an irrational fool, and their view is correct (and yes, this is the only thing that has changed recently...as people have become more exposed to people who aren't like them, they have retreated into their shell).
Btw, you should also consider whether your own view here has any "sense". Part of living in a society with other people is the right to disagree with others (isn't it odd that you use this right when considering the views of others but don't believe they have the same right? That their views just make no sense and can be ignored...irony).
It is unfortunate that fewer and fewer people today understand the principles on which their freedom is built.