Gotta be honest, I've never had a player ruin one of my games. Like, no one in real life has ever said, "You're railroading!" even though people here have said I do. No one has argued against my interpretation of spell variability (magic is unpredictable) or how my monsters differ from those in the MM (stat blocks aren't gospel).
I decide how a dragon's breath weapon works, whether orcs can track elves by scent, how quickly a particular troll regenerates or whether Magic Missiles can bounce. I decide how many dice a player has to roll for damage when they fall down a 50-foot crevasse. (IMO, a player should always be a little afraid to leap across a dark ravine, and I don't care if someone writes a 1,000-word essay about it.)
To the DMs of the world, take back your power!! Rulings before rules! People need structure, even when bloggers and podcasters say they don't. Be the sheriff of Table Town!!
Put down the rulebook, and be the benevolent dictator humanity deserves.
Now, bring on the hate, and I shall drink it like manna from heaven.