The number of potential obstacles barring humans in the future from creating such technology are too great.
One main form of the simulation theory suggests that advanced human civilizations in the future have created a simulation for the cyber-world we now inhabit. However, there are many potential risks of failure, preventing those civilizations from ever becoming advanced enough to prove the simulation theory.
Nick Bostrom, within his own 2003 philosophic theory, claims that a number of factors must contribute to the success of the advanced human civilizations in creating a complex universal simulation. Many critics and opponents of the theory itself believe these barriers to be too great for the simulation theory to ever become reality, citing the exponentially increasing unlikelihood in the theory ever reflecting physical matter as the complexity of hypothetical scenarios rises. Bostrom posits that the fraction of advanced human civilizations that would ever be able to reach this level of complexity in a simulation is incredibly close to 0. Additionally, the likelihood of "posthuman" civilizations looking to move backward in time to create a simulation for the many generations before them is very low. Even Bostrom, the man who practically invented the scientific and philosophical framework for the simulation theory, doubts the probability of such a phenomenon ever occurring. His tentative mathematical calculations disprove the theory itself because of the astronomical odds that it would ever truly exist.
Decreasing probability does not equate to the theory's complete lack of plausibility, which is why it is called a theory. Yes, there are many factors leading to the prospect of simulation that come across to mathematicians and physicists as unlikely now, but advancement in technology clears away all predictability for the future and there is no definitive answer for how far human can come with computing power. Many natural phenomena in the physical world seem unlikely when solely dictated by probability, yet still, they occur all around us. To completely discount the anomalies in the observable universe to refute the simulation theory is vastly illogical.
[P1] If the conditions for a theory to be plausible increase exponentially until the probability of the theory itself is virtually zero, that theory is automatically disproven. [P2] The simulation theory's probability lessens as the unlikelihood of its many conditional factors decreases, barring the theory itself from ever being truly proven. [P3] Therefore, we are not living in a simulation.
Rejecting the premises
[Rejecting P1] Lack of probability does not necessarily equate to lack of plausibility. In other words, an improbable premise does not always lead to an impossible theory. [Rejecting P2] Relying solely upon mathematics disregards all possibility for anomaly within the universe, and the simulation theory is not necessarily impossible if its premises are improbable. [Rejecting P3] From the evidence given, no one can definitively say we are not living in a simulation.