The company’s deep commitment to Mars colonization and Elon Musk’s nearly total control make SpaceX stock an astonishingly speculative bet, our columnist says. (Giulio Bonasera/The New York Times) By JEFF SOMMER Watching SpaceX stock trade in its infancy as a public company has been like viewing a successful rocket launch. The ascendance of the company’s shares has been pure spectacle. The superlatives are still piling up: SpaceX had the largest initial public offering in history, making its…