Perhaps the more appropriate question is: can we afford not to have one?
Public policy is always about choices, and there is no excuse for poverty in a society as wealthy as ours.
Consider this: the total cost of getting everyone in British Columbia currently below the poverty line (the after-tax Low Income Cut Off) to the poverty line is about $2.4 billion. That’s a lot of money. But in contrast, it is a mere 6% of the provincial budget, and 1.3% of provincial GDP. And recall that international institutions are currently calling on governments to inject stimulus packages into the economy worth at least 2% of their GDP (which in BC’s case would be about $4 billion).
And remember, the price of inaction is not priceless. We all pay for poverty through higher cost to public health care, the justice system, and community social services (not to mention lost productivity). Study after study finds that the cost of servicing the homeless is greater than the cost of housing them (for example, see here).
More more, see here.