“... men demand activities, even such that include a certain element of coercion mixed in them. Just as false is the idea that if Adam and Eve had remained in Paradise, they would have done nothing but sat together and sung arcadian songs and observed the beauty of nature. Boredom would certainly have martyred them as well as it does other men in similar positions.” - Immanuel Kant's The Metaphysics of Morals, my translation
Boredom in the Metaphysics of Morals appears as a theme and a term (Langeweile) in the context of ‘play’ – and notably, playing cards.
In a more extended consideration of the sources of playing in the lectures collected in the Philosophical Anthropology essays, Kant elaborates on the hookup of Eden, work, play, and boredom – for it turns out that, in circumstances where our needs are abundantly satisfied, boredom comes into play as the motive pushing us to work or to certain forms of play. It complicates an old equation that posits lack, or need, as the driver of work, or productivity – since boredom is not the same kind of lack as other lacks. What it is, however, is hard to say. “Boredom is the quintessence of unnamable pain.”
The importance of boredom in universal history has never been truly qualifed, since the topic seems to lead, by a neurotic defensive gesture, to moral shamemaking. Kant makes a good effort, though, to cast off the bourgeois shackles and examine the phenomenon coldly, beginning with a cultural universal that reaches all the way into the Canadian wilderness:
“The passion for play [zum Spielem – gambling is implied] is met with in every nation, even the Canadian savages like to play, while Chinese are given over to play to the point of mania, so that they bring their wives and children and even themselves into slavery through play. The interests [stakes] in play serve to enliven it and contain therefore such great charms that it constitutes the pastime for most of our society. The cause is that fear and hope continually change places in play…” 
The reasonable man, for Kant, then, plays with that alteration of fortunes in mind. Underneath this reflection, one hears the cracking and downfall of a long humanistic ideal – that of the good life as constructed in the classic tradition. It is not to mediation that the ideal subject, satisfied in all of his needs, turns – but to a flight from boredom. Play, gambling, is a way to make life adventurous again.
“A rational man, who sets down to play, can not have gain as his intent [Absicht], but he must believe, that he at least in the end must be paid for his stakes. Therefore his intention must be something else other than gain. During the play his intention is, of course, only to win, but he did not undertake participation in the game to do so. Here it is a purely a question of hope and fear, that are fundamentally vain; but one is distracted during these circumstances, and has distracted oneself from the one that one calls boredom. Such an evil, which is what boredom is, one commonly doesn’t know how to name, nor what countervailing means to apply to it. This evil of boredom springs out of the lack of activity.” 
The division between the game as a whole – which is played for the sake of being played – and the different moments of the game, the hands – which are played to be won – gives us, then, an activity that isn’t ‘serious’ – and yet one that fools boredom, playing its own game in the margins.
The boredom motif is oddly untouched by those economists looking at the hyper-financialization of late capitalism, where the incentives are all supposed to be about gain, or, for those on the left, about power. How much of a role does boredom play in the financial markets? Myself, I think boredom is the shadow side of speculation. We are prisoners of the boredom of the rich, we who are playing our games far below theirs.