I have an accountant friend that mentioned he was thinking about getting a rental property one day. I told him I thought that was immoral and his response was that he would charge below market rate. This implies that market rate is the neutral point in his moral system. Above that line is immoral and below it is moral. But market rate is the max that you can possibly charge by definition. If you charged above market rate and got a tenant, that's just the market rate now. It's impossible for him to be immoral in his system. All the while, he's setting himself up to build his wealth off of someone with less money than himself and increasingly benefitting off of a housing crisis.