Marek's disease and Covid vaccines

One thing I see discussed alot is why TPTB would want to kill off their useful idiots with a vaccine, leaving only the free thinkers and those that reject authority left.

I think this problem is resolved by their leaky vaccine. I think their goal is to have the dominant strain of coronavirus evolve to a degree that it is 100% fatal without vaccination. Much like how Mareks disease has done in chickens due to a leaky vaccine for that disease.

I fear the true endgame is total control through a life or certain death without a vaccine. Imagine the control over the population they could achieve with this.

Please tell me how I'm wrong in this thinking!