If it is a placebo, it is one hell of an expensive one! Far cheaper to just let everyone catch the virus, treat them as cheaply as possible, if at all, and wait it out until those who are going to die are all dead, and those who have "natural immunity" to it, if such a thing exists, can then inherit the world.
It would also take the co-operation of the thousands of scientists all around the world, of many different nationalities and philosophies, who have been and still are applying their various knowledge and experience of epidemiology to working against the clock to find a successful way to immunise against CoVid19. Unless you are one of the Luddites who believe all science is fake and all scientists are evil conspirators, it must be obvious that there wouldn't have been that co-operation and dedication for a mere placebo.
My fat balls bring all the birds to the yard
I'm not a pheasant plucker....
