"Dealing with people is probably the biggest problem you face, especially if you're in business."
There are far more great players today than there are paying jobs. The ability to successfully navigate the business side of music has never been more important. And by far the most difficult aspect of that is dealing with people.
Your reputation, both your musical one and your professional one, always precedes you. Those who are kind, even to those who sometimes make that difficult, tend to get called a lot. Sure, some people who are rarely kind get work, but they do so in spite of that fact.
With the current level of competition for even just quality freelance gigs, you don't want to be giving anyone a reason to not hire you, especially after putting in thousands of hours of work on the horn.