Socialism could work, as long as those producing food have the option to NOT feed other people and fully escape any consequences of not doing so, including bad conscience etc.

Then, those people who like to be charitable could be so to their hearts' content, until they get tired of it, when they can move away.

I don't know how you could set this up, but it would work then.

Otherwise given what humanity is at the present time there is inevitably going to be tears.

Or another fix: some sort of separation of people, coupled with a collective wipe of memories (so the different groups don't remember each other exist and so they don't feel bad about not giving or getting), coupled with subsequent careful population profiling and screening to memory-wipe and remove or re-sort any individuals that accidentally fall into the wrong boxes.

This way, people who are inclined to accept, thrive and grow on charity could be separated from those who give it. Charity would not cease but it would be naturally limited (there would always be unwilling parties in any charitable transaction) so a charitable society could be sustainable and not subject to parasitic kill breakdown. N.B an uncharitable society is sustainable, just not "nice".

Matrix:
A.charitable giver B.uncharitable giver
accepting (growing) taker accepting taker

C.charitable giver D.uncharitable giver
reluctant taker reluctant taker


From above,
Sustainable:
C
Nasty, sustainable, bad prospects for universal brotherhood:
D, B
On the road to oblivion:
A