And yet, you still can't make money.
Yup. It sucks to compete in a market currently being "nuked" by a cash rich airline with a penchant for predatory pricing practices.
Nobody is profitable in DEN right now, but amazingly, Frontier is about as close as you can get. "Close" only counts in horseshoes and hand grenades.
DEN is essentially a battle of attrition being waged by our friends at LUV. The only real hope for F9 is to fight the fight as long as possible and use whatever methods possible to improve their balance sheet in an effort to prolong the battle and inflate LUVs cost to win DEN. At some point, LUV may decide to adjust their DEN strategy and align their fares to more closely reflect those in every other market they fly.
It's really up to LUV as to how long they want to keep strangling. So far, F9 has held on a hell of a lot longer than they probably ever expected. If they desire to spend a few hundred million additional dollars and another year or so, then they will probably get what they want.