People change their behavior in other ways when the government pays with the taxpayers' money. After welfare became more readily available in the 1960s, unwed motherhood skyrocketed. The country is still paying the price for that-- of which the money is the least of it. Children raised by single mothers on welfare have far higher rates of crime, welfare and other social pathology.
San Francisco has been one of the most generous cities in the country when it comes to subsidizing the homeless. Should we be surprised that homelessness is a big problem in San Francisco?
Most people are not born homeless. They usually become homeless because of their own behavior, and the friends and family they alienate to the point that those who know them will not help them. People with mental problems may not be able to help their behavior, but the rest of them can.
We hear a lot of talk about "safety nets" from big-government liberals, who act as if there is a certain pre-destined amount of harm that people will suffer, so that it is just a question of the government helping those who are harmed. But we hear very little about "moral hazard" from big-government liberals. We all need safety nets. That is why we "save for a rainy day," instead of living it up to the limit of our income and beyond.
We also hear a lot of talk about "the uninsured," for whose benefit we are to drastically change the whole medical-care system. But income data show that many of those uninsured people have incomes from which they could easily afford insurance. But they can live it up instead, because the government has mandated that hospital emergency rooms treat everyone.
All of this is a large hazard to taxpayers. And it is not very moral.