A growing number of people invest in real estate they never intend to occupy and push up prices for the rest of us. Cities should make them pay. Down the street from my office, a luxury residential tower is rising, the fifth such project in Boston in the last decade. The 61-story “One Dalton Place” is being marketed as “New England’s tallest and most luxurious residential building.” Across the coastal cities of North America, cranes are rising to construct similar stunning new glass towers of both residential and commercial properties. Real estate in existing neighborhoods is being bid up by investors and wealthy buyers, pushing up the cost of land and housing for everyone else. A high percentage of these housing units will sit empty or rarely occupied. In Boston’s luxury Millennium Tower, for example, only 25 percent of the units are considered the occupants’ principal residence.