but they are offering 70 percent fare less from
Outstation any GCC Countries..The reason why they are offering lower, that's part of Airline Stratagy in order to take more passengers outside Qatar to join the Flight from Doha to any Destination they are operated.
if you compare Doha/Houston fare is higher than
Dubai/Doha/Houston the fare is less.

Not only Qatar Airways even EK/EY/GF/KU they are doing
the same..