Peterson's 12 Rules For Life, have you heard of this?

[Rev. Rye]

"fights monsters, make sure you don't become one yourself."

Because this assumes their is a bad way to fight monsters that leads to becoming one. If i fight coach roaches invading my house i don't become a coach roach.

• Oliver Cromwell fighting the absolutism of King Charles I and essentially turning into an absolute monarch in all but name.
  
• The oppressive and poorly-run ancien regime of Louis XVI being overthrown by the righteously pissed off people, who ended up becoming even more oppressive and poorly-run than their forerunners.
  
• The workers of Imperial Russia getting sick of the Tsar's bullshit and, in their attempts at trying to move beyond it, end up with a leader who has basically become the Tsar, except with a paper-thin veneer of concern for the people. 
  
• Well, many of the successful revolutions in Latin American history are perfect case studies of this happening: the Sandinistas, Fidel Castro, Augusto Pinochet, and Porfirio Diaz being the most obvious examples.
  
• Robert Mugabe took over Zimbabwe when it was still Rhodesia, with a really racist and hostile (more or less) colonial government, and still managed the impressive feat of ending up being even more brutal and dictatorial (and even more racist) than the Rhodesian government he ousted (as unrepentantly brutal as it was) was.
  
• The War on Terror, full stop. America responds to potential terrorist threats by ravaging countries that could potentially be the source of more terrorists, and in the process, young men from these brutalised countries get so fed up at the US' efforts to stop terrorism by fucking them over that they feel they have no choice but to become exactly the sort of monsters they saw the Americans as.
  
• The Algerian War of Independence, where the Algerians got fed up with the French colonists who were brutalising them, torturing them, and not giving a shit about collateral damage, and ended up overthrowing them... and in the process, blowing up shit-tons of innocent people and instituting what amounts to an Islamist dictatorship.
  

Need I go on?

Tizh, I envy your optimism, but I simply cannot share in that optimism. I look at history and see things happening contrary to what your confident idea would expect all the time. I look at the news, and I can see people falling into the same sort of traps their oppressors fell into (for just one small example, look at Rose McGowan's reaction to the Asia Argento affair), and if they keep doing it, I can't expect it to end well.

It's tempting to see the world as being in a black-and-white good vs. evil struggle, and while I can definitely see the black (and at its lightest, it's eigengrau), all the white looks grey to me, and the more ambitious the grey is, the darker a tone it becomes. And the greys with the lightest tones are the ones who are least likely to get anything done in the long run. Why, yes, that does suck.