re: Why are guns a right in the Constitution but not affordable housing?

You do have a right to affordable housing. You work and save and buy a house you can afford. If you want a bigger house, you improve your skills and marketability and find a job that pays more.
Everybody has that right.
"Life Liberty and the pursuit of happiness". This gives you the right to pursue happiness which can be defined how an individual chooses. If you want lots of money, you can pursue that and better your life and income and the govt shouldn't stand in the way of you doing it.
If you choose to work a job that requires no skill and the demand for it is low and it pays poorly, but you are ok with that, then that is your right to do it.

Your question goes against the Constitution and it's intent. The Constitution limits the power of the govt, what you are suggesting is giving the govt immense power to set rent prices, home prices, etc. That is the antithesis of the Constitution.
The Constitution does not give you the right to bear arms, it tells the govt that it can't take arms from the citizenry. So it is limiting the govt, not granting us a right. You are looking at the constitution @ss backwards.