CEO is a job. It's a managerial position. Usually, it is tied to some form of ownership, but not always. Choosing to take an active role in managing the company as a business owner does not mean your power does not come from ownership, nor does it mean you must take an active role.

Capitalists are necessarily exploitative and entirely unnecessary for running a company. You can have a CEO that owns a company just as much as the Janitor does, which entirely changes the source of the power and removes the ability to exploit the laborers. As an individual owner, a CEO can act in some manners that help workers, but will nevertheless be ruthlessly exploiting them in other manners.

I think reading theory might help you a lot.