Why do CEOs make 400 times more than average worker today compared to 50 times more in 1950?

Because the average worker is paid less today than in 1950 adjusted for inflation. A lot of middle manager/supervisor/skilled manual jobs have been dispensed with thanks mostly to Information technology and the de-skilling of manufacturing jobs. Profit maximization strategies eliminate middle cl layers of management with CEO of course being one of the few jobs that can't be replaced by technology.