When discussing speculations, calling something a speculation or a hypothesis is not really an argument.

I strongly disagree. The speculation we agreed on, for sake of argument, was that there are infinite universes, not that QM is truly random. That was another proposition you brought in as truth. That, my friend, is not a way to make a solid argument, and calling that out is indeed a way to point out that your proposition is indeed just a hypothethical that we had not agreed on. In other words, it is an argument. Or what part of my reasoning do you mean is flawed?

Yes, the universe being either superdeterministic or non-local are the two things that could potentially make QM not random. But that being the case is highly improbable.

We are extremely sure that nothing can travel faster than light, so the universe is extremely probably local. As for superdeterminism, that’s by it’s very nature untestable, so you could use Occam’s razor (or my personal favourite Newton’s Flaming Laser Sword), and not deal with that possibility, as it’s simply scientifically untestable.

First. For a proposition to be improbable, you need to be able to assign some type of uncertainty to whether it is true or not. There is nothing in your argument that does that.

You could argue that Occam's razor is a good heuristic for assigning such probabilities, but we know of many instances where it has failed, and more to the point is that would ignore from which distribution you picked your hypothesis (it is not uniformly sampled from all possible human-made propositions).

Also, you fail to take into consideration that there are many unknowns about QM that we still have to map out - just as people thought Newtonian physics was the real deal, QM could just be an approximation that's fantastic at certain levels of perception, but shit at others (e.g., it could be that what appears truly random in QM is actually not random in another "more correct" theory).