I would like the story much better if they had a lower percentage of people falling into the catatonic state. A third of people using the device going catatonic is too many. Two problems.

1) If I created a device that caused a third of people to go catatonic after using it, then my device is going to be pulled from the market. I believe tobacco products kill 1/3 of the people who use them and they're highly regulated. The difference of course is that tobacco kills after years and years of usage. The implication in the story (both from the wordage and the fact that the message is coming from a year in the future) is that the device causes you to go catatonic in weeks or months. Societies protect the lives of their members or else they're replaced by other societies that do a better job as they die out from their failure. Hearing about an unregulated 1/3 chance catatonic machine breaks too much of my suspension of disbelief.

2) If such a device existed, I don't believe that it would cause a 1/3 catatonic rate. Two things here.

2.1) At least in my experience, people tend to learn and act by intuition and compartmentalization. High functioning individuals don't seem to have necessarily better intuitions, they are just much better at compartmentalizing the inconsistent aspects of their life such that one area doesn't contaminate another. High level performance in complex fields requires internalizing many incompatible frameworks. If you can't keep them separate then you'll let your intuition from one sphere cause you to fail in another.

Of course I could be totally wrong, but it feels to me like this is how the real world works. Which is why the story breaks my suspension of disbelief when they give the 1/3 catatonic rate.

Most people would play with the device and have really heated philosophical debates. And then they would go on with the rest of their life like they didn't have a future prediction machine.

The only people that should really be affected by this device are people who are either already having some serious problems handling modern life due to really horrible compartmentalization skills or people who's entire cognitive functioning is structural. Of course modern society is really complex. Like, there's a reason why the logical AI techniques from the 70s are being overtaken by the statistical models of machine learning. There's just no way that 1/3 of people operate in a structural way such that knowing that there's no free will destroys their ability to function.

2.2) And of course the second thing here is that we already have a lot of soul crushing aspects of modern life that destroy our illusion of self agency. Do you have a dead end job that you can't escape? Do you have toxic family members? Do you have a terminal disease? Did an unexpected accident cause you to lose someone close to you or permanently damage your health or destroy property that you can't afford to replace? Do national events cause drama, distress, and chaos? So many things happen in our lives that tell us that we do not have control. If the human condition doesn't cause a 1/3 catatonic rate, then a 1 second future prediction shouldn't either.

EDIT: So the gut punch of the story is the end where the messenger indicates that free will doesn't exist in the long term (ie the messenger doesn't really want to send the message, but has to because free will doesn't exist). A 1 second lack of free will isn't scary, but a whole year lack of free will feels worse. Or at least it's supposed to.

But the fact of the matter is that I would rather be on a beach someplace relaxing instead of working for the next several decades. But I've got no choice. I'm already handling a lack of free will on the order of decades. Everyone is.

So I get what the author is trying to do and I think it's almost effective. But I have a hard time being emotionally sympathetic to the messenger in the story. Yeah, you were forced to write a message you knew about a year in advance. I'm forced to pay a mortgage for the next couple of decades. I'm having a hard time feeling sorry for you because it feels like I've got bigger problems.