Provide a rigorous theoretical analysis of Nick Bostrom's Simulation Argument. Break down the trilemma into its three components: 1) The fraction of human-level civilizations that are interested in running ancestor-simulations, 2) The fraction of post-human civilizations that have the computing power to run human-level simulations, and 3) The fraction of civilizations that actually run simulations. Discuss the philosophical implications if we assume we are currently living in a base reality versus a simulated one. Conclude with a reasoned estimation of the probability that we are in a simulation.