The difficulty is that given a choice between helping yourself or helping others, you'll help yourself first and help others with what you're comfortable giving up. That number is nonzero for most people, but it's also the lesser of the two for most people.

Charity and altruism are real things that hold societies together, but without institutionalization they lead to tribalism and exclusion. Rush Limbaugh is reportedly an extravagant tipper - he'll happily give up large sums of money to people who bring him a meal. That's altruism in a way. But Rush Limbaugh would also happily abolish the government's ability to collect tax - in other words, Rush Limbaugh supports altruism for those he selects. It's like the whole faith-based initiative clusterfuck of the Bush administration - want food aid? go to fucking church, infidel.

In order for a society to be fair, diverse and egalitarian, charity and altruism has to be distributed to people we don't think should get the money because they reflect views and cultures other than our own. Rush Limbaugh is not going to support "welfare moms" but reducing poverty requires that welfare moms be supported. Leave it up to personal choice, and...

...well, the Saudis are big on charity.