“Exist” is always too heavily loaded in these discussions. And it’s always a hoot when STEM-y people do philosophy. What a mess.
I don’t feel like writing a ton tonight, but as one of the commenters points out, math is just a model of the world. It and probability is “real” in the sense that it relates well to something phenomenologically experiential.
And as usual, no one in that discussion understands quantum mechanics at all or what it means, like the doof talking about Geiger counters. Completely wrong. We could know the entire history and state of every bit of everything in the universe and we still could not predict when a bit of uranium would alpha decay and trigger the counter.
And if you then base some other event on that alpha decay the Geiger counter registers, you’d have something operating that even knowing the entire prior history of the universe would not have been able to reveal to anyone would occur. In other words, all empirically successful quantum interpretations are probabilistic. And this is not (as it is with classical probability) due to lack of knowledge. That’s the moronic (and wrong) interpretation. The probabilistic nature of QM and reality is a fundamental aspect of the universe itself.
So, is probability real? No, it’s a fucking model. Just like nearly anything else useful in science and math.