Apple, Google, Facebook and Amazon have created products and services enjoyed by billions of people. But their size and reach into our daily lives also is cause for concern. Scott Galloway, a marketing professor at New York University, shines a spotlight on the dangers of letting Big Tech invade our personal lives without a second thought in his book, The Four: The Hidden DNA of Amazon, Apple, Facebook, and Google . He recently spoke on the Knowledge at Wharton show on SiriusXM channel 111 to explain why people need to pay attention. The following is an edited transcript of the conversation.   Knowledge at Wharton: These four companies have come very far in a relatively short amount of time. While they have certainly reaped the benefits of the internet and gathering of data, what other common factors have propelled their growth? Scott Galloway: Since 2008, these companies added more market capitalization than the GDP of India. The value accretion and influence is just staggering.…