The problem I have with this question is the false assumption that it is those in Real Estate who create the problem. The problem is demand and lack of supply and high demand. Economics 101.
A big part of the problem here in California is incompetence and ignorance.
Here is a quick, off the top of my head list of some contributing factors which OP overlooked:
1. (Many intertwined points here) City Mayor, Council and State Legislature offer benefits to businesses to come. Those businesses bring increased wealth to the cities which bleeds into the local populace by way of spending and demand for goods and services. Workers from around and outside the area strive to work for the higher wages and better quality of life offered, an influx of workers move toward the city. Local businesses and workers thrive and demand more. Without increased housing and multifamily supply, rental and housing prices go up. Here is an infographic illustrating this here in California: https://infogram.com/california-bands-together-1g43mn7yrl062zy
2. City/State governments ignore the increased demand due to more workers in the area. This puts further strain on the existing, insufficient housing supply. Without increased housing and multifamily supply, rental and housing prices go up. Another illustration of the ignorance and incompetence by elected officials to proactively address these problems: https://infogram.com/waning-construction-1h0n25xgryoo4pe
3. City Mayor, City Council and State Legislature promise big benefits(here in CA, Overpromise) to state workers in a bid to buy votes. This strains the budget greatly. Taxes and regulations increase as well as enticements to companies so they come and pay taxes to balance these budget shortfalls. The workers have more money to spend and what happens? They demand better housing accommodations with their increased purchasing power. Without increased housing and multifamily supply, rental and housing prices go up.
4. Overburdensome laws and regulations. The complexity to get new housing and multifamily built has exacerbated the building of new homes and multifamily. This has put downward pressure on the supply of new housing and multifamily units. Some factors:
- Local growth initiatives designed to stem the overpopulation of areas
- Often misused Environmental Laws pushed by local residents in opposition of new development.
- New development opposition and reviews by local residents in the form of hearings, etc.
- Redundant governmental reviews by many different departments.
Just a few things which came to mind that exacerbate the already messed up housing supply around the country. Gentrification is a symptom of major problem and to say that those who rehab and build homes and multifamily are to blame for gentrification is, in my opinion, flat out wrong.