Think of it this way, how many times has our civilisation run the Grand Theft Auto simulation? What about all the future GTA session that we haven't run yet. It's got to be many many millions.

Now GTA isn't a very sophisticated simulation, and the characters don't have much AI, but either no civilisation ever develops the tech to make a "realistic GTA", or no civilisation ever wants to run a realistic simulation, or there are many millions of realistic simulations in existence.

And if there are many millions of realistic simulations, and only one real universe, it's literally a one in a billion chance that were in the real universe.