Why some people are hot tempered?

I did a quick search.  Some of the reasons why some people are hot tempered?

They are insecure

Sometimes a person loses his temper when he gets others totally wrong. People who are insecure usually believe that others are making fun of them or disrespecting them. Such a way of thinking can make a person lose his temper very often.

Their anger gauge is already full

People who have some unsolved problems that make them angry are very likely to lose their temper faster. The accumulation of such problems results in making the person's anger gauge almost full that he explodes as soon as anything happens.

           They are impatient

Impatience can contribute to short temper. A person who is very impatient is very likely to lose his temper fast compared to a patient person.

They are dissatisfied with their lives

People who are dissatisfied with their lives are more likely to lose their temper fast. The fact that those people are unhappy yet don't have control over their lives motivates them to release some of the frustration they are experiencing through anger. 

What is the best way to deal with some one like that?  I am still trying to figure it out.   In the meantime I'll just try to avoid them?