Maybe revoke the incentives for those who currently already own multiple properties. No sense in putting an additional financial barrier to people attempting to purchase a home to live in. Investors will be slightly affected by this but it seems like the type of measure that would deter first-time homeowners altogether- therefore exacervating the problem of so many properties being taken by people whose primary interest is profiteering, and leaving those who just want to own the place they live in the dust.