Im guessing they have very little competition and high load factors. At 504 frames, the cost of 4-6 fleet types is roughly 400% of 1-3 fleet types. This could easily be a $300-400m a month penalty. So, if they hade $2.5 billion, they could have made $3.7bn. The other guy, how many planes does he have? At the same 500 planes, 12 fleet types, cost could easly be 1200% of 3 type cost.
Also, when you say 4 Boeing, I assume that is like 737, 747, 757, 767, not 737-700, -800, -900, -900ER?
Edit: Being a beginners world helps eith those profits significantly. Neither of them would likely survive a full world with thise numbers, especially the second guy.