Fine, ill play your game.
Travis to me is not just a villain or a freak, though his actions are something evil or malicious, overall his heart is always in the right place.

The entire film he struggles to find a meaning or purpose to his life, and when he “finds” it by fighting crime, the first thing he does is try and take out a political candidate out of sheer childish and petty rage in hopes of being killed simply for being rejected by Betsy, the only reasons he chickens out is because he knows the secret service is onto him already.

Travis wanted to leave a legacy behind, ever since the start of the film he talks about becoming a fighter against scum and a legend amongst the streets, and i believe that’s why he’s not a purely evil character.
If he just wanted to kill somebody before going out, he could’ve easily shot some random bystanders before turning the gun on himself, but since he truly wished to do something good on the world, he goes against Iris’ captors.