Why do you study Martial Arts

I have heard hundreds if not thousands of opinions on What is the best fighting system. But few have ever given me a reason why other than it looked cool. It got me thinking, What are Martial arts? The least biased means I could come up with is definitions. 

 MARS -     The Roman name of Ares, the Greek and Roman god of war.

MARTIAL- inclined or disposed to war; warlike:

Martial arts-    are codified systems and traditions of combat practices, which are practiced for a number of reasons: as self-defense, military and law enforcement applications, mental and spiritual development; as well as entertainment and the preservation of a nation's intangible cultural heritage.

Arts of Mars           art of war

Reasons for violence

Personal.  =physical or verbal l ,intimate  relationship  executed by family,friend,lover caretaker

Law enforcement
Para military

Sneak attack, supperior numbers, gun, knife,or blunt instrument

Threat or display of violence to achieve a goal,theft,rape, intimidation

A greed upon criteria to engage in combat
Opponents square of on some what equal ground(swords,guns ,combat sports.

All can be valid  reasons to train but what are you practicing for?