how do you get accurate information on how people think?

Some people, though, are VERY open about their thought process & beliefs, such as the Buffett & Munger duo; also Winston Churchill - a lot of what he wrote about includes himself as a player on the game board. These people are pretty open and honest, and there are others like them.

If whoever you're trying to learn from is highly private or secretive (Steve Jobs comes to mind) you're stuck with second-hand information, though good journalists are able to collect meaningful data samples on pretty much anyone famous.