What decisions do you make differently with your knowledge that free will is an illusion? What choices do you make differently?
(fwiw, I agree with you; I just think it doesn't particularly matter now.)
Interestingly, my belief in the illusory nature of free will has had a huge impact on my life. I'm a much more laid-back person than I used to be. I don't stress out so much over making mistakes. It has also helped me in a lot of practical aspects of my life. For example, it has helped me lose weight. I think about my desire to eat as my brain playing a sort of a trick on me, and that makes it easier for me to "decide" not to give in to the craving. I treat the part of me that wants to eat the cookie as a separate entity from "me" that just happens to reside in the same brain, and I interact with it through internal dialogs like I would a small child. It sounds weird, but it works, at least for me. I'm almost down to the same weight I was in college (and I'm 54).
Horizontal gene transfer? A literal virus that changes who you are. It's interesting to think that by going paleo or vegan you can perhaps become another "person"...