The man in charge of public health at the time openly encouraged people to attend the victory parades. Other public health officials pleaded for people not to attend
The first wave killed 3-5 million. The second killed 20-50 million.
One aspect to the increased deaths during the second wave was people becoming infected at the same time. This led to a surge on hospitals hitting at the same time. Not only did those with the virus die before they could be treated, but non-infected emergencies were unable to be treated. This led to exponential death rates.
When the second wave hit, places like San Francisco refused to wear masks in public. They also stopped social distancing. San Francisco ended up with one of the highest fatality rates in the US.
Moral of the story: even if your state “opens up”, stay home if you are able. If not, wear a mask, wash your hands, and practice social distancing.