All our actions and decisions are indeed merely the machinations of a predetermined universe. Our concept of free will is indeed naught but an illusion. All this is what in Philosophy circles is called a trivial truth, however, for we humans scarcely know what the ultimate limits are behind the realities of either free will or predetermination. We do not know what they, in truth, mean in the greater context of the entire universe. Our feeble brains draw a blank in these areas that we are not even intelligent enough to acknowledge we're even doing.

This is to say that telling a human that it is limited in its will is like telling a quark that it only has the Milky Way to travel through, outside of which it is not allowed. It's range of travel is "limited" to only this galaxy, in other words. How long do you think it would take something the size of a quark to be able to traverse the entirety of this galaxy alone? This is to say that it is an absolute absurdity to lament a limitation not even a fraction of whose extent we are likely to ever even come close to expiring or reaching.

It's like giving someone 5 billion trillion dollars and telling them that they can "only" spend 4 billion trillion of it.