In my current FtF game, one of the party's first acts was to kill both of the rival crime bosses who dominated a small mining colony (the bosses fell to fighting over the cargo that the PC's had brought to one of them and the party then decided to kill the victor). The party was hailed as conquering heroes by the common miners. When they departed a few days later, they left an elected council in charge of the colony.

But . . . they had done nothing to address the root causes of the crime bosses original rise to power (off-world interests that preferred to biddable strongman governments compounded by the transient nature of the colony populace - NOBODY regarded the place as their home).

So when the party had occasion to return to the world several weeks later, they found their council deposed and yet another strongman in power . . .