It is never a wise idea to bite the hand that feeds you, no matter how tempting it may be.
For most normal, well-adjusted people, treating those who provide us with a service with respect is a total no-brainer. So long as they do their job properly and are reasonably respectful, why should we be angry? It is not like it helps things get done any better.
Unfortunately, anyone who has worked in a customer-facing role realizes that there is a startlingly large cohort of the population who do not seem to share this logic. All they care about is getting every last thing done to their exact and often unrealistic specifications, and somebody or other is going to suffer if that doesn’t happen (spoiler alert: it rarely does).
It is difficult to be an employee in this position. You can’t talk back for fear of professional consequences, but the customer truly believes they are always right. Depending on the behavior, though, it is sometimes possible to take action so that they do not bother you in the future. Nobody should have to deal with people like this in their job, even if some individuals seem to think that is the case.