There are many lessons here, but the most important one is this: Despite his celebrity, commercial success, and prodigious talent, David Foster Wallace committed suicide at age 46. As a leader, you are going to be dealing with different people all the time. You must be humble and understand you will never understand what's really going on in the heads of other people. Regardless of how happy, extroverted, brilliant, or grounded a person looks from the outside, their inner world will always be inaccessible and may be vastly different than you expect. And when in doubt, be nice.