Responsibility is shared jointly. If you merely drive the getaway car for a bank robbery in which a bank guard is killed, you yourself are fully on the hook for murder. If Trump had taken Covid seriously and advocated common sense mitigations like wearing masks, socially distancing, and refraining from unnecessary activities, our position would be significantly better. As a public figure, downplaying the problem while advocating irresponsibility is at the very least gross negligence. This puts him on the hook for the entire outcome. I agree many other politicians are responsible for their part as well, but that's besides the point.