[Mz]

Not a single industry per se, but a major social problem offering potentially multiple business opportunities:

Homelessness is on the rise nationwide in part due to a serious lack of genuinely affordable housing. Among other things, in the 1960s and 70s, we tore down a lot of SROs. The Baby Boom generation was an anomaly. The unprecedented wealth of their parents was due to WW2. Yet, expectations from that era still shape housing policy and infrastructure, much to our detriment.

You do not necessarily need to be a construction company to play a role in addressing this issue. Another very serious problem is the lack of financing mechanisms for housing alternatives. For example, co-housing projects in the US tend to be self financed because we do not have financial products that fit them. This actively undermines their ability to add affordable housing to the system, a purpose they successfully serve in other countries, from what I have read.

There are, no doubt, many other things one could do to work on this issue.