The expression "human endeavor" has a meaning of its own, perhaps best defined through usage, as in this quote from Albert Einstein:
The most important human endeavor is the striving for morality in our actions. Our inner balance and even our very existence depend on it. Only morality in our actions can give beauty and dignity to life.
Perhaps we can say that a "human endeavor" is one in which humans strive to achieve something of significance, or something of significance which can only be achieved via human intelligence, ingenuity, and/or willpower.
"Humanity is surrounded by illusions and common men are the playthings of the imperious urge of destiny. There is no sphere of human endeavor what is out of the reach of the tyranny of fortune and capricious circumstances." Leadership, Abridged, William Russel White, 1956.
"The world-wide interest in sports constitutes a most potent medium for influencing the thinking of the peoples of all nations. Certainly no other phase of human endeavor so captivates the imagination or arouses the emotions and enthusiasm of the youth of all lands ..." The Journal of Health and Physical Education, January 1937
"From astrophysics to microbiology to behavioral science, one common thread runs through all research – the human element. Science is an intrinsically human endeavor. It takes human curiosity to ask the questions, human logic to design the experiments, human ingenuity to incorporate the results into an evolving model." Ever on and on (anonymous blog), 2013
In your example (as Lambie mentions) the expression is likely sarcastic, since gambling is not normally considered a significant human achievement.