Why would you assume this? Do you have any studies that back this up? My default assumption, way more logical I'd say, would be that they want to steal stuff. Stealing is logical and rational, under some circumstances. Attacking someone (so putting yourself at risk as the attacker) or killing someone (again, putting yourself at risk immediately and after) are not rational.
Why would you assume that they want to kill or harm you? I'd say that I have Occam's razor on my side with this one. Stealing stuff makes waaaay more sense and again, can be quite logical in many circumstances.