These are actual statements from other Minecraft players, word for word from various PMC forums. Keep in mind these posts do get stranger as they go on. These players know, but they don't realize the truth.

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"Same here... I cant stand to play minecraft bymyself..
Its just that your alone.. Forever.. Without any purpose..
Anything you do in the game will not matter.
Sometimes when i build a huge mansion.. Thats when it kicks in..
ive added bedrooms and balcony n bathrooms.. But theres only me..
so i ask.. Why bother?.. Whats the purpose?.. Is there an end?
Once you become so immersed into the game its like the movie
I am legend.. Anything living out there is trying to kill you...you cant have peace at anytime
you really are alone without any hope that will change.
Except one difference.. Theres no death and no end.
Funny thats how real life is.. There is no set purpose.. No goal..
We have to make them ourselves..
Then you realise to appreciate death and we also have each other "

"I find it kind of scary in an existential way. Sometimes during slow periods of gameplay, like smelting a buttload of ores, I stop and think.
What is my purpose in this game? Who am I? Why am I here? Why am I building great things that only I and creatures I'm meant to slaughter will see? What is the value of something that I cannot share?"

"Paranoia is a pretty useful evolutionary trait. If you are with a group of people, your senses are not as keen and you are not as aware of your surroundings. This is because you feel safe. More eyes and able bodies give you that sense of security. If you are alone, your paranoia kicks in. Your senses become heightened and you become aware of your surroundings. Since their is no one around, you lose that sense of security. From an evolutionary standpoint, this trait helps you stay alive.
So why is single player in minecraft creepy? Because you are alone. If you get really involved in the game, you feel the same as if you were alone in the real world. So, paranoia kicks in; every rustle is a mob trying to kill you, there is danger on the other side of every block, the landscape transforms from a pleasant vista to a life wrenching death trap, etc. "

"Minecraft singleplayer is a bit scary, but it is of course, because your alone.
Theres no one else on your blocky earth, but you. Alone forever, trying to find silly diamonds and save the world from a dragon when it doesn't really matter because there is no one else to save. No one else to help you with your house. No one to help you kill that creeper. As many others have said, again, this is because your alone. Forever."

"this is the reason i like playing multiplayer with a friend instead of singleplayer
Singleplayer just gives you that feeling that there is something watching you, while there is nobody at all "

"In my opinion, Minecraft is an extremely existentialist game. You place blocks,fight monsters, mine ores.....and at the end of the day, once you've set up your castle/village/cave, you just stop and think,"Now what? Everything's done. I've gone to The End, beat the Enderdragon...so now what?" You just keep on living. Some find it extremely lonely, so they download Humans+ or something of the like ,but in my opinion, these are simply quick fixes."

" have sounds happen in single player that never happen in multi and I thought I was freaking out. I've heard long drones, gongs, dragonish howls, etc... wtf are all these strange noises at times? "

"I don't find it as scary as much as I find it lonely and melodramatic.
The feeling that the mobs are out to get ya.. and you feel as if you are truly part of the game, then you stand back and realize your just playing a popular computer game. Then you realize your mind has been tricked into thinking their is a danger without other people to protect you which is hardly as prominent as one thinks, hence the use of melodramatic.
It probably is something to do with the fact that Humans weren't made to be alone.
We need company. So a game about solitude might be strange. That is just my take on it though.
There is always the reason, of course, that is:
There is something following you in Minecraft. I don't know what it is, but it hunts its victims through video games. GET OUT WHILE YOU HAVE THE CHANCE!!! "

"I do get an unnerving feeling sometimes in single player. Maybe that explains why I always end up living in, or close by, a village. Last night, for example, I was branch mining and I was in this 1X2 tunnel, I must have gone close to 500 blocks and all of a sudden I got this bit of claustrophobia and I wanted to get out of that tunnel as fast as I could. It doesn't happen often but, yea I know what you mean, sometimes the loneliness is kinda creepy. "

"Well, look at it this way, imagine you woke up tomorrow, and every single trace of human life was completely gone, except for you. It's kinda like that in a way, it would take forever to explore the whole world, and you don't even know who built the many things around you and why they did it. Why are there jungle temples? Who knows... Who's going to help keep your alive, and do the many jobs the world once had being performed daily? Besides, then nobody is there to watch your back, to give you encouragement and care when you need/want it, it's all on your shoulders to keep yourself alive and sane, just being concerned about what might sneak up on you and just end your entire life in one fell swoop. I could go on all day, but this should work for right now. "

"You are alone in a world, which is inhabited by animals and at nights by vicious creatures such as arrow shooting skeletons, swarming zombies, giant spiders and green thing that stalks you to explode at you. The only living, humanoid and friendly entities are villagers, who are incapable of defending themselves, often walking into places which are highly dangerous. You can live with them if you want, but you have to remember to deal with zombie sieges where the vicious zombies of night want your and the villagers dead. The world is full of dark caves, full of resources and vicious creatures who again, only want you dead. The world is huge, and you will never quite conquer it all. You have to get food, build a house, build weapons, mine minerals from the dark mines, explore the dark dimension of Nether, and eventually destroy a giant flying dragon. All by yourself. So yes, the world of Minecraft would maybe not be the nicest place to live in."

Now, where's yours?