Provide a detailed analysis of the Simulation Argument proposed by Nick Bostrom. Discuss the three premises: (1) The fraction of human-level civilizations that reach a post-human stage, (2) The fraction of post-human civilizations interested in ancestor simulations, and (3) The fraction of all observers that live in a simulation. Evaluate counterarguments regarding the computational feasibility of simulating consciousness and the problem of infinite regress. Conclude with your own probability assessment of us living in a base reality versus a simulated one.