Is there any sector of the economy where private rent-seeking isn't a major component of profits?
No. The payment of the factors of production is always in large part politically determined, so all profits (and all wages, for that matter) are always in large part zero-sum rent seeking.
- Jake If you only spend 20 minutes of the rest of your life on economics, go spend them here.
And that is precisely why market architecture will continue to evolve - driven by increasingly direct connections - to a dis-intermediated model within a partnership framework.
In fact, the evolution of 'for profit' transaction intermediaries to service provision is ongoing, because capital requirements are thereby minimised. Moreover, a partnership framework is inherently co-operative, and within such a framework there is no profit and no loss. "Any economic unit can emit money. The serious problem is to get it accepted" Hyman Minsky