Complaining is admission of one's subservience to a situation. It's a way of expressing dislike for it (which is understandable), while implying that they are allowing themselves to become a slave to it.

Winners are never slaves, even when they're physically shackled. They witness the same undesired situation that the losers witness, but they accept that as their starting place, and move forward from there to improve that situation. In doing so, there is no room or time for complaining.