I don’t see why neighborhoods should have to allow more homes to be built. America is huge and mostly empty, there’s tons of land to build on before we start trying to ruin existing communities. When I hear this it just sounds like trying to set the precedent of screwing people out of their land. Your mention of profit sounds like trying to do so without fair compensation, which currently is at least required for eminent domain.

Yes, there's lots of houses in suburbs with empty bedrooms. If there was an incentive for boomers to rent rooms in their houses like in the 1920s. But that is risky for the boomers.

How about to reduce risk, but reward lucky ownwes, a lot of houses too big for aging boomers, could have incentive payments to sell to HUD to convert into rooming houses, with lockable bedrooms rented separately, and the shared kitchens and bathrooms cleaned by HUD, and quick evictions for any troublesome renters. So more like renting at a YMCA or backpackers' hostel, ideal for the working poor.