I have a theory as to why some people drive with their hazard lights on. I'm referring to those that have them on even though there is no obvious reason for it - they are traveling at the correct speed, no visible damage, not hauling over-sized cargo etc.

The reason is that the individuals that activate their hazard lights whilst driving, were first told to do so by their peers, relatives, or parents, whom always did it as well, and also suffers from one or more of the following:

1. Has limited driving skill and finds it difficult either mentally or physically to perform effective evasive maneuvers if necessary. 
2. Has poor vision. Cannot see clearly most of the time and refuses to wear corrective lenses (or cannot afford them).
3. Has virtually no confidence in their own ability to drive and accepts that condition for life. Refuses to get further training.
4. Feels that the hazard lights are a "shield of invincibility." That if they are on, they are safe from anyone hitting them.
5. Does not have any practical knowledge of the mechanics and physics of driving an automobile. Remains conveniently ignorant. Wants to communicate their special status to others.
6. Doesn't have any desire or will to maintain their car, or finds this to be an annoyance, thus they are not trusting of the car's soundness. These people usually slow to a crawl over any sort of bump in the road too. Especially railroad tracks.
7. Possible that the individual is deliberately being defiant, or purposely non-conformant i.e., to "make a statement."
8. Wishes to be noticed, and to stand out from other drivers as being special or elite. i.e., "presidential motorcade." 

Please add to this list if you can think of any more.