You can get diseases. Untreated, some of these can be fatal. Others will just make you wish you were dead. Feces are, after all, concentrated human waste -- the stuff we eat that our body can't use. If you're into this, you need to proceed with great caution, and be prepared to tell a medical professional about it when you get sick. Considering your digestive system has E. Coli in it to break down the food, would you want E. Coli in your body?
It is not okay because there is bacteria that could kill you. That would most likely make you very sick and is not a very hygienic idea. Please do not eat human feces.
Not as a rule. Dogs regularly eat poop, for three reasons: they may get insufficient vitamin B in their regular diet, they may be getting too little food, and they may want to 'hide' their traces or those of a pack member (especially puppies) from possible predators. People very rarely eat poop, but although it's yukky, it's completely safe if it's your own: any bugs that poop may contain are already inside you. Eating somone else's may be a health risk if the other person has a typically 'poop-related' disease like typhoid fever. You might die by catching the illness and then doing nothing to cure it.
They eat for the same reason you do: to stay alive.
To stay alive
All living things will have to eat to stay alive. == ==
No every person needs to eat to stay alive
to stay alive
They might not have to eat all the time but I know that they must be constantly swimming in order to stay alive.
yes
Same reason all animals eat - to get energy to stay alive.
Koalas eat in order to obtain the energy and nutrition they need to stay alive.
to get all the nutrients it needs to stay alive
yes
Yes, because it needs to eat to stay alive.