Scientifically, I think it's hard to argue free will as everything that will ever happen was set in motion from the beginning of time. Every action is just a reaction to something that was set in motion. However, philosophically, I feel free Will exists, but possibly is not able to be proven.

That being said. If we have no free will, but you believe we do have free will. You had no choice as that in itself is your predestined belief.

If we do have free will, but you believe you don't have free will, you are trapped by your belief into a thought process that is closed to all the possibilities in life.

To me, the belief in free will allows for accountability for one's actions and to take control of your destiny. If I am wrong and I don't have free will, I will never know and will have walked the path I was meant to walk.