Building more housing is tossed out as if this is a single dimension economics problem, like widgets in Freshman econ. Perform a capacity utilization study of all available housing, where Capacity is the number of room days of housing available and utilization is the amount it is actually occupied. Then tag each of these housing units (room) across multiple dimensions including cost, location, house, apartment, condo…
Many economists have proven over and over that building more housing means that there are more places for people to live. The burden of proof is on you, since you are the one making outlandish claims.
The number of "underutilized properties" is likely a few percent in your area. "Most condos are empty and owned by foreigners" is a myth perpetuated by NIMBYs and conspiracy theorists.
Even if it was true, the best way to screw over these shadowy foreign empty-building-owning figures would simply be to build more housing so that it's not an artificially scarce investment asset. The value of their investment would plummet and they would have to sell it or take on tenants.