I get that people want to root for vigilantes that take justice into their own hands against corruption in a system, but you don't change systems with random one-off actions.
Changing system-wide problems is either very long and painful (voting, activism, community organizing etc) or long and very painful (wars, revolutions).
One man with a gun very rarely changes things. It's when people come together and fight (peacefully or otherwise) with common goals in mind that real social progress is achieved.