If that what Hamas goal, then mission accomplished

A destabilized Middle East benefits the West, not Hamas. The US' interests in Israel and Palestine are largely geopolitical. Pouring money into the conflict and keeping the region in chaos serves to keep the Middle East fractured and thus not a unified threat to the US. Hamas certainly aren't interested in furthering US geopolitical interests, but it's an unavoidable side effect of advancing their actual goals.

This is why the US is happy to provide military assistance to Israel, but also cry foul if Israel decides to try to wipe out Hamas. They want to keep a Goldilocks level of conflict. If there's too much, it'll burn out, if there's not enough, it's not helping their resource (oil) extraction.