Risks of shared Wi-Fi
The question is, do you trust the person that maintains the wireless network? Do you trust the other people that are using the wireless network? There are all kinds of risks when you connect to someone else's network. For example, man-in-the-middle attacks, DNS hijacking, etc.

I'm not saying you shouldn't use the shared Wi-Fi in a group home, but just be aware there are risks connecting to any network that you don't control.

A security researcher, Troy Hunt, recently published a blog article on a related subject. He is explaining why he doesn't allow guests to connect to his home Wi-Fi, but the risks he mentions hopefully explain better some of the things that can go wrong with Wi-Fi networks. No, you can’t join my Wi-Fi network