The United States is a society of excess. Yet, we still let people starve and go unsheltered. There is an easy solution that doesn't have the unreasonable expectation of the poor relying on the goodness of other people: tax individuals with high incomes at higher rates. The marginal tax rate for the highest income earners has steadily fallen in the past decades. People with those high incomes have the least marginal utility on their income and should have a higher tax burden on the portion of their income which isn't necessary for their comfort.

This isn't to say that charitable giving is bad. If you are financially stable and have money to spare, please donate your time or money to those that need it. It just isn't the solution to a national problem.