I don't understand the usefulness of determinism. If it is true that free will does not exist it still seems more useful to believe that it does at least to an extent.

Personally a lot of things in my life are modeled around the idea of free will and have it as a foundation. I view myself as having chosen my job, chosen what to eat. What to do as a hobby etc. At a personal level it seems that believing in determinism instead of free will would wreck much of the foundation of how I organize and go about my life.

It seems that this is true for the vast majority of people and is reflected in society. With other major beliefs there are work arounds that allow you to change how you live your life and move on if you change your belief. If you switch religions you can adopt new customs. Similarly if you become Atheist you can focus on non religious things to adapt your lifestyle.

The same could be said for other major belief changes, like political views, moral values, historical understanding etc.

But I don't see how this works with determinism. How do you effectively run your life if you don't believe that you have control over how you run it. It seems like an oxymoron.

Not saying determinists can't life a full and nice life, but I don't understand how determinists cope with not believing in free will. It just seems like believing in free will whether or not it is true is incredibly helpful.