It might help if you were more specific. What version of Mac OS are you running and what version of PS CC? It looks like you have a total of 8GB of RAM, which isn't very much. I just launched 2018 on High Sierra where I have 16GB RAM, and it opened with 7.99GB used by PS. I have no image loaded, and a total 0f 13GB used by the computer with a couple other apps open.
Now I do happen to have a lot of presets loaded right now. I vary that considerably depending upon what I'm doing, but lots of brushes, big patterns, layer styles, they all use RAM. On top of that, if you actually use PS, it does try to hold on to memory so the app performs well, but if you're not using it, I gather the system can pry it loose if needs be. I don't know that what you're showing indicates a memory leak. That usually means that it opens at one level of memory and doing nothing, it ramps up the memory called for over time. But someone from Adobe can help you if they know more about the system you're running.