There's high demand now but a new building has to earn its keep for many decades. They're skyrocketing because of x, and x is because of y, and y is… the ultim

There's high demand now but a new building has to earn its keep for many decades. They're skyrocketing because of x, and x is because of y, and y is… the ultimate reason is that too little is being built. AFAICT too little is being built because while it's easy to find tenants for a new building now it'll probably become difficult within the lifetime of a new building.