I hope he didn't suffer too much.
It could happen to anyone. Not necessarily smoking in bed, but starting dinner and laying down on the couch "to rest for a minute while dinner cooks". Or it could be someone who throws a load of laundry in the dryer, puts the kids to bed and falls asleep reading them a story.... while the buildup of dryer lint catches fire.
Most of the house fire stories on the news end with, "there were no batteries in the smoke detector" or "there were no smoke detectors in the house".