For better or worse, real estate is one of the earliest investment opportunities available for the most Americans. The ROI is easy to understand and capital is much easier to access compared to VC, bespoke business loans, etc. The industry is large and competitive, not investing or participating in the market isn't going to actually change housing affordability. Almost everyone except the poor/working class is invested in real estate directly or indirectly.

Most importantly, only residents vote in local elections and it's local policy that has the largest impact on housing supply and renter protections. Market's are quick to react to policy changes but policy has to actually change - advocating for individual actors to behave against the market is, on average, not going to actually help the people you aim to help... instead other actors (and perhaps actors biased to even more amoral decision making) will take advantage.