The way people talk about it makes it sound indistinguishable from "random will". If you believe in the existence of a "self" in any form, be it the chemical signals and electrical impulses in your material brain, or a ghost existing outside of space and time controlling your body like a puppeteer, you must believe in one of you believe in that self having free will.
Say you were to run a scenario many times on the same person, perfectly resetting every single measurable thing including that person's memory. If you observe them doing the same thing each time then they don't have this quality of free will? But if you do different things each time are you really "yourself"? How are your choices changed in a way that preserves an idea of a "self" and isn't just a dice roll? Doesn't that put an idea of free will in contradiction with itself?
Edit: I found this article that says what I was trying to say in much gooder words
TBH, I'm not personally very interested in this concept of free will. I think we have to act as though it exists whether or not it actually does. But if, I were, say a moral philosopher, I would probably be very concerned about it because it underpins all my other assumptions about right/wrong.
Often times, there's stuff that's extremely critical to a specialist and less so to a layperson. Literally theorists will stab each other to death over interpretation, meaning and language because that stuff is at the base of all their work.
I'm not personally invested in it either I just know I hear about it a lot and, even though philosophy makes my brain feel like it's overheating, I find it compelling and interesting. If you put a gun to my head I suppose I would say I don't believe in free will, but I don't think it's absence will cause people to start eating babies without feeling guilt or whatever.