Before we talk about how much it costs to house all of our citizens and neighbors, it's important to understand that we have been spending more than three times the cost by leaving the problem unsolved.   Housing all of our citizens would cost about 28.8 billion dollars.  The numbers fluctuate a little bit, but for the past 20 years there have been approximately 3 million homeless people.  We managed to find an apartment for my son in Chicago--an expensive market--for $800 per month.  28.8 billion may sound like a lot, but there are more than 750 billionaires in the U.S.  The top 4 are each worth more than 100 billion dollars.  Any of them could end homelessness and still have more than 100 billion dollars.  That's a lot of $400 cheesburgers with gold flakes, $30 cups of Esmeralda Geisha coffee, and private islands.   In any case, if we spend 28.8 billion, we save about 100 billion in taxpayer dollars currently spent on dealing with the homeless population in emergency rooms, jails, emergency shelters, and motels.