It is neither selfish nor greedy to accept and use a gift freely given to you.

Receiving a gift does not confer obligations on the recipient.

True, but you would probably still be pissed if somebody took your gift and hit you over the head with it.

It does. There is an implied expectation that the recipient will will not be selfish. They can pay it back, pay it forward, possibly later when they can afford it, etc., but they are expected not to be selfish and also give someone something eventually.