In 25 hours of CQC combat with 545 kills, I've earned 341,359 cr.
That's still enough to maintain a Corvette!
Only concern is any system that generates rewards from interaction between players is open to be gamed.
So is anything that generates rewards.
Combat rewards should really be a zero (or negative) sum game. These assets come from somewhere, and while losses are handwaved when it comes to NPCs, it should be difficult to earn more than the other side loses in a strictly PvP encounter.