The referee runs the table. The referee adjudicates the rules, makes rulings when the rules are silent, and describes how the world responds to character actions.
The referee does not own the game. The DM, the GM, whatever you call the person at the head of your table – that person does not own the game.
Players are responsible for adding goodness to the campaign. The best players do more than show up for the game on time. They use their characters to create dramatic and action-packed scenes. They draw maps, manage treasure, make downtime requests, propose plans of action, and take initiative. They have their character sheet memorized and they don't need to look up their class abilities, spells, or magic items in the rulebook. They sit down and they really play the game.
A player cannot contribute positively to the campaign by thinking only of themselves or their character(s). They can't be a good player simply by making their character good. They need to make the campaign better. (Of course, this became more dire in Dungeons & Dragons 2.5 and later, where "optimizing builds" became a "gameplay" "feature.")
Listen: the campaign is all there is.
If a player's choices make the campaign worse, they have played poorly. If their choices make the campaign better, they have played well. Sometimes this means increasing their character's power. Sometimes it doesn't.
All this is predicated on mutual respect between players and referees, and a shared understanding of what makes a campaign "good." Referees and prospective players should align on this matter before the referee accepts them as campaign participants. A player's definition of "good" must align with the referee's "good." In the case of players uncertain or new to a culture of play, they must at least buy in to the referee's definition. The player must be willing to try it on for size in good faith, with the understanding that the player will leave the campaign if it doesn't click for them.
The referee, on the other hand, must run the game they want. Capitulating to player desires in this matter is a recipe for disaster. The referee has, by far, the greatest investment in the campaign. It's always better to take the time to find the right players.
"When you build your campaign you will tailor it to suit your personal tastes. In the heat of play it will slowly evolve into a compound of your personality and those of your better participants, a superior alloy." – Gary Gygax, AD&D DMG p. 7