So, on the one hand I have people with no political or personal agenda who have been studying for decades this very thing, and on the other you have a man who lies constantly, paid someone to take his SAT and has a vocabulary that would embarrass my 6-year old. Who do you believe?
The other reason we were told that we did not need to wear masks is because we didn't know enough yet, (new virus and all) and admitted as much at the time.
As soon as research showed the initial ideas were wrong, scientists said so and changed their recommendations. Would you prefer they doubled-down on their first thoughts months after they were proven wrong?
Lying is different - we should know as we see it 23.3 times/day from our president.