I feel like this is a reasonable counterargument. My response is that you can reasonably and ethically seek a profit with real estate investment because pieces of land are not people. And any harm you do to people is going to be extremely distributed across the population. Like, if you went around to everyone in your city and whistled an annoyingly saccharine tune next to them while they walked to work on a Monday morning, maybe the total negative utils would add up to a single human life of slavery - but I still think distributed harm is far more justifiable.