Abstract: Galaxy clusters, the most massive gravitationally bound structures in the universe, represent the extreme end of hierarchical structure formation. While nearby clusters have been studied in great detail, the earliest stages of cluster formation — the protocluster phase — remain less well understood, largely due to a lack of large, spectroscopically-confirmed protocluster samples identified using uniformly selected apertures and overdensity tracers. Next-generation observatories, with their wide fields of view, ultradeep imaging, and high-resolution spectroscopy, will help address these challenges. However, cosmological simulations of galaxy formation remain essential tools for interpreting existing protocluster samples, making testable predictions, and guiding future protocluster surveys. In this talk, I will share insights from my recent work with high-resolution zoom-in simulations of galaxy clusters, quantifying how observational biases — favoring the most massive and star-forming protocluster galaxies — impact our ability to identify protoclusters and influence the common interpretation of these structures as sites of accelerated galaxy evolution in the early universe.