a reasonable law to pass would be to make it illegal to rent a property until or unless you have paid some amount, x, of the price of the mortgage, and i would put x as higher than 75%. that is, in order to rent a property out, you'd have to have already paid at least 75% of the mortgage off. they should actually put you in jail for breaking that law, as well.

this would prevent people from putting minimal down payments down just to get property to generate profit from. capitalists are actually supposed to hate that kind of lazy, idle bourgeoisness.