You must live in a very different society than those in Europe or America if your experience with theists has just been “people hypothesizing.” You also must not have read the Bible, Torah, or Quran. Their “beliefs” are presented as facts in all three of those religions, both by their holy texts and their people, and I don’t know of any religion that doesn’t also do that.
If not, it’s absolutely arrogant to tell them they’re wrong to believe in the existence of something that science is also only hypothesizing.
And again, nobody is saying they’re wrong. We’re saying they don’t have good reason to believe what they believe. Just look at the link you sent earlier.
And if an atheist genuinely believes their own untested hypothesis about what happened before the big bang is true, whether they’re a scientist or a layman, the same criticisms apply to them, too.