Most of your other "big" car companies are also experiencing down-trending sales. Perhaps not the the same percentage as Tesla, but as soon as people are told to hate something/someone else, sales will go back like they always have. People have a short attention span - and only a minority of people wear their politics around as some sort of identity. An even smaller minority of the people cheering on the "downward spiral" of Tesla were ever going to be a Tesla customer (ie. a luxury brand car buyer).
The "downward spiral" of Tesla is greatly exaggerated.