Because if your house goes underwater, you keep living in it for years until it recovers and grows. With leverage on equity you get margin called during drops that kill your investment and give you no capture of future recoveries.
Can somebody please explain to me how these people continue to live? I’m sure many people want to quit their jobs and just walk out. But how would one pay rent, food and expenses? I’m not too familiar with welfare, but even for that don’t you need to be looking for a job?