There is an argument that free will doesn’t exist because there is an unbroken chain of causality we are riding on that dates back to the beginning of time. Meaning that every time you fart, scratch your nose, blink, or make lifechanging decisions there is a pre existing reason. These reasons might be anything from the sensory enviornment you were in the past minute, the hormone levels in your bloodstream at the time, hormones you were exposed to as a baby, or how you were parented growing up. No thought you have is really original and is more like a domino affect of neurons firing off in reaction to what you have experienced. What are your thoughts on this?
I think there may be a paradox hiding in your question. You cannot believe in free will. You have it or you don’t - I would postulate you need a neutral third-party observer to tell you. For us humans, a Martian might do. Believing is an act of faith. Faith tends to bend will to its dogmas. I would go so far as to say belief is the natural enemy of a free will.
We are distracted animals. All things being equal, the Martian observer will after years of careful study come to the conclusion that humans have free will. But it’s constantly battered by short attention spans, a tendency to go with the herd, presupposituons in our heads that we don’t often or never question, etc. We are a smartphone full of bloatware running on too little RAM. It takes skill to operate. Some are more skillful than others.
You could of course counter that by saying that’s what you believe. It’s paradoxes all the way down.