If you find yourself engaging in carpet bombing, carrying out large-scale terrorist attacks, destroying vital civilian infrastructure, de facto maintaining an open air prison (or if you want a more ironic term, "ghetto"), and creating a track record of "double-tapping" to kill first responders, deliberately killing clearly marked unaffiliated aid workers and journalists, deliberately and directly firing at unarmed civilians with live ammunition to "disperse" them, killing your own citizens held as hostages by bombing their captors, deny any possibility of a ceasefire or peace deal that is not an unconditional surrender, and protecting citizens who engage in illegal occupations, expulsions and vandalism in a way that effectively results in an ethnic cleansing in direct violations of UN resolutions and then call every critic "Hamas", "IS" or "Iran" while simultaneously stating that your military campaign will not stop before "Hamas" is eliminated permanently...

... then maybe, just maybe, you've become as much of a monster as the ones you claim to be fighting.

The ends don't justify the means. The means define what ends you can achieve. If your ends are "living in relative peace and safety" (and for the sake of realism we take that to mean equivalent to a country in Western Europe as neither of those things can be guaranteed nor permanent) and your means involve deliberately killing 10x as many people as your enemies while also killing more women and children and not stopping before the enemy is guaranteed to never pose a threat again, then your ends are only achievable if you completely exterminate not only every single militant sided against you but also all of their friends and family who might be motivated by your actions to take revenge. Or more likely, you'll end up outnumbered, outgunned and at the mercy of those who had to endure unspeakable suffering because of you.