Evidence that suggests it does make a difference whether you believe in free will or not.
Since google spies on my conversations this popped up this morning…
"Actually, a growing body of evidence from psychology suggests belief in free will matters enormously for our behaviour. It is also becoming clear that how we talk about free will affect whether we believe in it.
In the lab, using deterministic arguments to undermine people’s belief in free will has led to a number of negative outcomes including increased cheating (http://journals.sagepub.com/doi/abs/10.1111/j.1467-9280.2008.02045.x) and aggression. It has also been linked to a reduction in helping behaviours (http://journals.sagepub.com/doi/abs/10.1177/0146167208327217) and lowered feelings of gratitude (http://journals.sagepub.com/doi/abs/10.1177/0146167214549322).
A recent study showed that it is possible to diminish people’s belief in free will by simply making them read a science article (Free to help? An experiment on free will belief and altruism) suggesting that everything is predetermined. This made the participants’ less willing to donate to charitable causes (compared to a control group). This was only observed in non-religious participants, however.
Scientists argue that these outcomes may be the result of a diminished sense of agency and control that comes with believing that we are free to make choices. Similarly, we may also feel less moral responsibility for the outcomes of our actions.
It may therefore be unsurprising that some studies have shown that people who believe in free will are more likely to have positive life outcomes – such as happiness(https://www.tandfonline.com/doi/full/10.1080/09515089.2014.996285), academic success (The freedom to excel: Belief in free will predicts better academic performance - ScienceDirect) and better work performance (http://journals.sagepub.com/doi/abs/10.1177/1948550609351600)."