As a lifelong Chicagoan and an Ivy league-er myself, I can attest to the fact that the Chicago trading community is loaded with my fellow alumni. After all, this was the only place in the country to seriously trade derivatives until recently. Even now, despite the prevalence of screen trading, Chicago is still the Mecca of the derivatives world.
Like all things in the financial market, this confrontation is about money. Specifically, the fact that the Merc's monopoly power threatens the OTC derivatives market. ELX's investors are some of the primary players in the OTC derivatives market, so it makes sense that they would try to create a rival to the Merc.