Well, no, "you're not only making money," doesn't fit if your losing money, but I digress. Destroying infrastructure certainly has it's place in the context of a raid, but you're really telling me the Vikings went out pillaging to destroy people's infrastructure? If it wasn't profitable no one would do it. Raids throughout history have been to make money. Sure, hampering your neighbor's ability to field armies and feed their people is an essential secondary function, but the money is always the primary purpose, and it still doesn't fix the underlying problem you've presented by forcing a cap of two bullis on each soldier each raid; no one will use knights (at least, they'd be wise not to) if they cost eight times as much as a spearman to do the same damn thing. 

EDIT: 

In fact, are you not endangering your own production by raiding in the first place? Cut crop production, paying out the wazoo for upkeep on soldiers, etc. If you fielded your own one thousand three hundred soldiers over a year you'd actually lose 34,500b, and approximately 10,920 crops (at infertile production rate, would have to know the fiefdom the soldiers specifically belong to in order to be more exact) to make 5,200b and destroy some infrastructure which I seriously doubt is actually worth 29,300b to begin with. I mean, the fiefdom would have to be pretty rich to be worth that much, wouldn't it? How much crop displacement you cause would have to be factored in, true, a variable I don't have access to, but your wealthiest fiefdom doesn't make that much.