Yes, they really do. For most atheists, it's themselves. It's the idea that they possess the power and the ability to understand and control their own destiny, through reason. They see no power greater than themselves. And they see no need of any. They ARE the highest power in their conception of reality.
This is simply a false stereotype. Reason is the approach to help understanding, but it certainly doesn't give power to control. For example, the sun is clearly a 'higher power' over which humans have no control. That doesn't make it a deity. There are many, many things over which neither I nor anyone has control. Many are quite relevant for my 'destiny'.
There are many people smarter than I am. There are many people more knowledgeable than i am. There are many people better at almost anything you can imagine than I am.
So, the question isn't whether there is a higher power; there clearly are many powers in the universe far more powerful than any human or even all humans combined. it is not a matter of controlling destiny, although understanding *can* help with that occasionally.
it is a matter of whether we should lie to ourselves by constructing a pleasant myth rather than seeking to uncover the truth however unpleasant it might be. And yes, we *do* hold self-honesty as a very important value. Your type of make-believe goes directly against that value.