Ending to Taxi Driver - hallucination/dream sequence?

SPOILERS

At the end of Taxi Driver, Travis makes a recovery, reunites Iris with her parents and gets one over on Betsy.

I can't help but feel put off by the ending - Travis isn't a good person, doesn't make good choices yet in the end is a hero. It just doesn't feel right.

However, if you view the final 3 minutes as the hallucinations of a dying man, a desperate man trying to convince himself that he was a righteous warrior, the ending no longer seems out of place.