I would neither agree that we cost UA money nor that the numbers are insignificant.
Of course UA shovels millions of pax per annum but with the hordes of 1Ks and UGS on this site, times their large number of flights, the resulting volume is massive.
A single 'domesticated' 1K accounts for >100 pax per year and an international one like me still did count as 48 pax in 04. So the numbers are far from being negligible.

Also, all the UGS must - by definiton - generate a lot of cash for UA.
There are cheap 1Ks, and I like to travel cheap too - but mostly I end up buying flexible fares or book on short term. And hence I generate UA profits involuntarily.
Not that UA does not deserve that money though.