I'm going to be unresponsive to my friend that wants to hang out often.
Why are you going to ghost them?
I want to be the only one who decides when I have the time to hang out.
Wanting to choose when your alone time is understandable but, your friend may not have someone else to talk to or hang out with. They may have an underlying issue like being depressed or needing help, so I would suggest you try and be with them when you can.
Nah, I'll just leave them waiting. I do it because I want and it's fine.
It is your choice to make but you should think about how it might feel to be on the other side of the situation. Consider how you would feel if you needed help from your friend, but they ignored you instead. Hopefully understanding how they feel can help you make a better choice here.