Originally I would have said that it was to get in better shape, and learn some potentially useful skills, without the boredom of expending energy to simply move an exercise machine through its paces.
Lately, I have been reading a lot about Values, the cyclical nature of history and where our civilization likely is in these cycles. The Chinese civilization has lived through many cycles of history, with peace and war ebbing and flowing with the dynasties of the ruling elites. Much of the history of Kung Fu is bound up in this dynamic.
In my understanding of this, empires expand, and the core groups and favored vassal states get to reap the spoils of the empire, raising the standard of living of those groups. As the empires reach middle age, these spoils get less and less per capita. The next step is that the elites, trying to maintain their piece of the pie, drop the standard of living of the serfs, who then become restless. The dynamic then imposes more controls on who can have effective means to resist the additional taxation or complain about the rising inequality. Normally this involves a disarming of the lower classes so that a small number of warrior elite, such as the Samurai, can continue to extract their tribute. This leads to effectively two sets of laws, one for the well connected and another for the little people. A single Samurai/Knight/Warrior could dominate a large village because he was the only one with weapons. The medieval martial artist could upset this dynamic, despite being reduced to agricultural implements and bare hands. But why was this better than simply switching one boss for another (better in the view of the little people, of which I am one)? The difference is in the values held by those same martial artists. Those without values above dog-eat-dog are recorded in history as Warlords, brigands, and other undesirable terms.
My Values involve fairness, and do unto others as you wish those to do you”. Am I perfect? Not by a long shot, but I am trying. To me, a Master Martial Artist is never a victim, but is able to simply choose his response to whatever the world throws at him, realizing the world itself does not care if it is fair or not.
I am in Kung Fu because it helps give me the power to choose, regardless of what the world does around me.