“If it's true that we are here to help others, then what exactly are the others here for?”

Its not true but, if it were, they are too.

The others are here to demand that we carry their sorry asses through life.

J Carlton has it right.

(-; Carlton, I like it - a lot ;-)

Substitute "vampires" for "others", and it makes more sense.

The "others" are here to make the democrats look good.

;-) Same thing is true for 'the common good' -- somehow we are each responsible for everyone else EXCEPT ourselves.

 If everyone accepted responsibility for themselves there would be plenty of unnecessary altruism.

You and the "others" are here to positively and cooperatively contribute to the social and technical mechanisms for the maintenance, promotion, and development of the life process. Actually each and everyone's personal involvement requires so much personal individual responsibility, we don't have to much time to tabulate the others individual practices. We're too busy tabulating our own activities.