The answers to the three questions
What is the probability that it is possible to build at least two simulations?
What is the probability that there's anyone who can do it?
What is the probability that this someone has done it?
could be anything one wants between 0 and 1, from impossible to necessary. If you find it hard to believe that simulations are real you could set those probabilities closer to 0. This would be your belief.
Eric Schwitzgebel describes belief as follows:
Contemporary analytic philosophers of mind generally use the term “belief” to refer to the attitude we have, roughly, whenever we take something to be the case or regard it as true. To believe something, in this sense, needn't involve actively reflecting on it: Of the vast number of things ordinary adults believe, only a few can be at the fore of the mind at any single time. Nor does the term “belief”, in standard philosophical usage, imply any uncertainty or any extended reflection about the matter in question (as it sometimes does in ordinary English usage). Many of the things we believe, in the relevant sense, are quite mundane: that we have heads, that it's the 21st century, that a coffee mug is on the desk.
One can then look for justifications for whatever beliefs one has about simulations. Be aware that one can rationalize things that aren't true. Regardless, how would one rationally justify the belief that these probabilities are not just close to 0, but are exactly 0?
One could argue that any simulation of our universe would have to, in particular, use a Turing machine to simulate human understanding. John Searle's Chinese Room Argument suggests that this is not possible. If Searle is right then the probability is indeed 0 for all three questions and a rational justification of setting the probability to 0 for all three has been found.
Schwitzgebel, Eric, "Belief", The Stanford Encyclopedia of Philosophy (Summer 2015 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/sum2015/entries/belief/.