Brad Lightcap of OpenAI.Courtesy: OpenAIOpenAI appears to be growing quickly despite increasing competition. The San Francisco-based tech company had 400 million weekly active users as of February, up 33% from 300 million in December, the company's chief operating officer, Brad Lightcap, told CNBC. These numbers have not been previously reported.Lightcap pointed to the "natural progression" of ChatGPT as it becomes more useful and familiar to a broader group of people."People hear about it throu...