Hey, this is something that is eating me up lately and I'm not sure what to do or where to turn. Some context to the title:

I have a very good friend who I've known for years (he and his fiancée are both going to be members of my own wedding party) who I care about a lot. That being said, he comes from a family where his parents started their own company and both they and his brother do landlording on the side. He usually has a cycle of thinking about joining in and then backing out, and he is back in that mindset again. He's very frugal so he's saved up quite a but and after getting furloughed for a while he seems a bit more serious than usual. He's aware of my politics and I think I've been slowly making him see the light, but I'm at a roadblock. How do I tell this guy that I don't think he should be a landlord because they are scum, without also saying that I essentially think his family are scum? Is it even possible? I just feel like I need to say something if I want to call myself a leftist actually dedicated to making the world a better place. Thoughts?