People who say this don't know how bad simple unarmed robbery or home invasion can go. There was a case around my area where a teenage home invader was caught by an elderly man. The thief tied up the old man and his wife to chairs and left them. They sat there for 2 days. If not for a vigilant neighbor, they would have died.
Regardless of original intent, many robbers will value maintaining their life (staying out of jail) over your life. You shouldn't expect anything different and need to treat them accordingly. Theft is inherently violent and warrants death.