Claim: Star City is home to a secret underground city built by Elon Musk to mine Bitcoin using free geothermal energy from a dormant volcano.
Verdict: Fake. While Elon Musk has invested in geothermal energy projects and has discussed Bitcoin mining in the past, there is no evidence of any secret underground city being constructed in Star City, Russia (the actual cosmonaut training hub) or any other place named Star City. This is a fabricated conspiracy theory merging his real-world ventures with fictional sci-fi imagery.