He'd turned schools into death-camps, he'd had everyone and everyone who looked too smart killed, and he'd had people worked close to death and then buried alive, Pol-Pot's reign of terror was without a doubt an insane and dangerous one but what did he want to gain from doing it all?
Essentially, Pol Pot's (and his CPK Center circle of powerholders') aim was to make what Chinese communists had attempted before them:a"great leap forward", meaning a forced, sped-up transition of an agrarian society into an industrialized one. into an agrarian state that would yield enough goods to be self-sufficient. Industry was supposed to be just existant to support agriculture.
A main, if not the biggest, influence of Khmer Rouge ideology was Maoism. This can be seen from the way the Khmer Rouge implemented production plans that were to be achieved and rigorously enforced. The Khmer propaganda even copied Chinese rhetoric, stating that their "workers are engaged in an unceasing offensive aimed at a very spectacular Great Leap Forward. " [1]
That ideology, for the Red Khmer, came at a very high cost: Being an economy that relied heavily on rice production and export, the Khmers first aim was to establish that sector as their base of national self-sufficiency. This part of their ideology, however was rooted in economic tradition, as well as nationalism [2]
The consequence of this trail of thought, paired with a strong anti-intellectualism [3] was that Cambodia was to be transformed into an agrarian economy (even more than before) by expelling the 'bourgeoise' class from the cities into the rural areas and forcing them to work in the fields, leaving a massive shortage of employees/workers for the industrial sector. In addition, the Khmer dismantled the already existing industrial sector to free up work force.
So basically, this Endgame of the Khmer Rouge was to create a self-sufficient at the core communist nation (but with many influences outside of communist ideology, such as nationalism, khmer traditions, and some others), with the main source of income being an excessive production of rice. The revenue from their exports was then to be used to start and further industrialization. [4]
However, due to their genocidal persecution of all kinds of minorities, as well as an Infrastrukture incapable of supporting the massive extensionnof farming rice, yields, and thus money, were usually scarce and it didn't really come to much economic growth under the Khmer Rouge.
Another factor, which i left out here, because i don't have sufficient sources, is the economic burden of constant war with Vietnam.
[1] Radio phnom penh Broadcast, quoted in: Ponchaud, François: Cambodia. Year Zero, New York 1977, p. 109 [2]rice: Etcheson, Craig: The Rise and Demise of Democratic Kampuchea, Boulder 1984, p. 29; nationalism: Etcheson, p. 52. [3] Jackson, Karl: The Ideology of Total Revolution, in: Jackson, Karl (Ed. ): Cambodia 1975-1978. Rendezvous with Death, Princeton 1989, p. 71. [4]Chandler, David: Brother Number One. A Political Biography of Pol Pot, Boulder 1999, p. 116.
Hope this helped.
EDIT: I rephrased my first paragraph after the many input comments, correcting a mistake concerning the focus on agriculture. Sorry for any misconceptions prior to the edit.
Was there any history of the Khmer people turning on each other, or stoking long-term resentments before the revolution? It seems unthinkable that they would inflict such cruelty against their own people without a precedent.