It sounds like your friend is really creating a great space for people to experience something different. I am not sure I see this as generous, as I tried to explain, I think we get more from people who we host than they get. They get a bed and a warm shower, we get to meet new people and get experiences and stories from them that we would never know ourselves.
Please look into couchsurfing, even if you do it once in your life, it will be worth it.