And the mainlines are going bankrupt while low fares make money. RJs really don't allow people to bypass hubs as they normally fly to the hubs from smaller markets (SBA-LAX or DEN, FAT-DEN...). They just fly people into hubs so they can bypass security (maybe). The low fares use far bigger planes than RJs (around the PAX capacity of what UA and AA fly on 762s, more on jetBlue), out of smaller markets and/or airports, and fly with frequency. They make money because they take into account economies of scale and are not so greedy with margins that they cannot sell tix.