I think the scariest part of Minecraft is more of an existential terror. It's the realization that you're completely alone in single player. You can get your pets, the villagers, and all the mobs, but that'll never fill the void of missing players. It's terrifying when you realize that as long as you're in single player, even if you build the most extravagant castles, the most impressive bases, and the most amazing temples and shrines, but it's all an attempt to fill the void of loneliness. It's the thought that, eventually, you will run out of ideas. You'll run out of mobs to kill. Run out of achievements to to get. Run out of builds to make. Run out of farms to make. You'll run out of things to do and then, sitting in your massive cities and looking over your empire, you'll realize that you may be at the top, but it's easy to be number one when you're the only number.

-Master Oogway

JK, real credit to @ anotherwofartist5895 on youtube