I think these are understandable and well intended questions! But they also makes it seem like you're not very familiar with standard economic analysis. I would encourage you to read The Rent is Too Damn High by Yglesias which is by an american (leftist) who I think has a much better set of ideas for improving the lives of renters than "occupation friendly" housing regulations and other "zero sum" ideas. And yes, buying and administering rental properties is societally valueable just like running a bakery, restaurant or software consultancy is.
https://www.amazon.com/Rent-Too-Damn-High-Matters-ebook/dp/B...