You really don't understand how real estate works, Alexander. Shelter speculation doesn't "bring in cash." Outsiders spending money at restaurants, cinemas, amusements parks, etc brings in cash. Shelter speculation simply outbids local working money so it can install a hose pipe to siphon wealth out of that society for years to come. So the local economy loses twice: First because shelter prices skyrockets, second because wealth is drained out in the long-term.