Uber investor Jason Calacanis has advised investors to buy Bitcoin directly instead of purchasing MicroStrategy shares. Calacanis criticized MicroStrategy, suggesting a 75% likelihood that his recommendation will be validated. The company's stock has dropped 35% from a high of $457, facing criticism from short-sellers like James Chanos over its premium to net asset value. Additionally, MicroStrategy's recent stock issuance policy and exclusion from the S&P 500 in September have raised concerns about its future Bitcoin acquisition capabilities.