D&D is a GAME

Play Nice and Get Along!
People tend to forget that D&D, White Box, 5e and other role-playing games are just that - games. Nothing more. It isn't a story, or a movie, or a novel, or even a comic book, just a game. It isn't a lifestyle or a community, it's just a game we play sitting around a table, or online, with friends who also enjoy playing the game. It's shared entertainment.
Players roll dice. Sometimes the dice are in your favor and sometimes the dice are not. It is a game about rolling dice and winning stuff, or losing stuff. That stuff consists of imaginary coins, hit points, gold and gems, PC levels, magic items...even character death...and it's all just game mechanics. Nothing is real, except the fun and the friendships.
Whose game is it? I think it's everyone's game. Group ownership, shared ownership, is a tricky thing for some people to grasp. Gary seemed to think it is the DM's game (he says as much in his Advanced Edition Dungeon Masters Guide and elsewhere). Today's popular internet culture often says it's each individual player's game, in other words, it's your game. Then again maybe it's the license holder's game (many lawyers think so)?
Does ownership really matter?
It's a game that we play together for fun. None of the gold is real, we don't win or lose money playing a table-top role-playing game (I am glad we don't!). It just doesn't make sense to be selfish about our game.
It seems rather simple. Remember to play like you care about the others at the table. That is how friendships are eventually formed. It's also the best way for everyone at the table to enjoy each game.