I'm going to let my friend's house get robbed
How would you  know their house is being robbed? Do you have anything to do with it?
I don't know how that's connected to me. I'm just staying home.
If you let their house be robbed they will need to borrow things from you. I don't think that would be pleasant for you to do all the time.
You're right. If something illegal is happening, I should report it.
Good, and your friend would be appreciative of you doing that.