The church and the state have worked so hard to convince people that they are bad an/or owe a debt to society. "Pay your fair share"...

Even if they realize the negative effects of Altruism, they have two big road blocks to tossing it away.

Road block 1 - People in general prefer being part of a group, the larger the better. Objectivism is based on individual rights and responsibility. A base group of 1 requires more self confidence than many people will ever have.

Road Block 2 - Just in case mind set. Those that are not enamored of Altruism still like the largesse of others it promotes. Even though nowadays little, if any, is voluntary. After all, that largess comes in handy if you have problems yourself. So they support it weakly, Just in Case.

I suppose. Many are driven by guilt as well.

Because the negative effects of altruism are not so obvious to many non-Objectivists.