It's not just free will, it's the whole individual that goes along with it. Everything is everything, it's all just one system, and since nothing can be taken away or added to it, and furthermore it could very well be that everything dissipates into nothingness either way -- so much so that would be impossible to even tell a difference between outcomes if there was anyone left to make the effort -- and if even the people are just figments of their own imaginations with no real choice about what to want, then how am I to argue for happiness or against cruelty, rationally? How am I to justify any action or thought or uttering, ever? If you want to prove irrationality is not required, show me the rational argument. I never could come up with one that doesn't lead to a circular "just because".

So in the meantime I accept that my desire to do or not do a lot of things is irrational which also implies I pretend there even is such a "thing" as "me", separate from everything else, for which there is no rational basis either. When you say "accept irrational beliefs", I think that presumes a baseline of pure rationality which I doubt any human ever achieved. So while I loved that quote and thank you for it, I also have to say that it might go both ways :)