I Used to Be Homeless
To live in, In SF. your choices are a 1.5 million dollar condo or a 50$ dollar tent.  Seriously people, we need to allow for more choices than that.  I'm sure builders and entrepreneurs would line up around the block to build solutions that are cheaper and more cost effective, but you first have to make it legal (get rid of the mountains of regulations and zoning headaches that make this problem so insurmountable), without that, will never make any progress on this problem.Why do you think the internet took off as quickly as it did? or the facebook app store in 2008, etc.  It's because there were no regulations (or almost none).  This allowed thinks to take off very quickly.Let's designate a section of several cities, say a 1 square mile section as regulation free, with an absolute minimum of zoning requirements, and almost 0 regulations.  Then let the market have at it, see what gets built.  Sure, maybe you don't like what happens in version 1.  But, if we never iterate on this problem, we'll never make progress on it and in a 100 years we'll still be talking about this same self imposed problem which is completely solvable.