Twice this month at the indoor shooting range where I'm a member, I've had nitwits in adjacent lanes negligently point their weapons at me while they were reloading or adjusting something on their guns. Yes, I told them to knock it off, but WTF?
The range employees tell everybody "Always keep your gun pointed down-range" and this is a fundamental of all gun-safety instruction. Where do these idiots come from?
The way I generally handle it, if it is the first offense of the person sweeping their muzzle, is to let them know why that is dangerous and show them a safer way to reload, check a malfunction, etc and keep the muzzle pointed down range. If it happens again, I ask them rather curtly how they would feel if I would point my weapon at them. That generally puts a bit of a fire under their arse.
I'll echo what many others have said, at some point we all were guilty of this in our earlier days. The reason for this is that most people just don't practice enough. There are four stages of competency:
1) Unconscious incompetence (when you have no clue that you are doing anything wrong)
2) Conscious incompetence (when you do realize what you did is wrong, but still did it anyway)
3) Conscious competence (when you realize that your actions are correct and have made the conscious decision to do them)
4) Unconscious competence (this level is what we all should be striving for... this is when you are doing the right procedure from muscle memory through much practice)
These levels are the reason why solid firearms owners PRACTICE PRACTICE PRACTICE. The more you practice (and practice correctly), the more you will have ingrained in your unconscious memory to do things in a safe manner without thinking about it. And trust me... stop practicing for awhile and your muscle memory can deteriorate. So KEEP PRACTICING!!!