Venture investor and LinkedIn co-founder Reid Hoffman, 56, was one of the chief architects of the social media age. Now he's turned his attention to artificial intelligence. Besides investing in OpenAI, he's a co-founder, alongside Karén Simonyan and Mustafa Suleyman, of the Palo Alto, California-based Inflection AI. To date, the trio has raised $1.5 billion from Bill Gates, Eric Schmidt, and Nvidia, among others, to build Inflection's personal intelligence AI solution, dubbed Pi.