Yes, the investors are the symptom and not the cause. They are going where the money leads them. However a big problem with institutional investors is that they also institutionalize NIMBYism. They won't just block housing in a select neighborhood, they will block housing everywhere and they put more pressure on the federal government to ensure that housing is protected as an investment class. Both will contribute to worsening the issue.

Plus even at low levels NIMBYism is often about investment. Sure, many object to new housing for reasons like "it will change the character of the neighborhood". But many others object because they are worried about the value of their own home going down. They are treating their home primarily as an investment because that is what they have been told to do their whole life. If I could snap my fingers and magically realign our political goals to maintaining stable home values instead of having them ever-increasing, many NIMBY objections would fade away.