How about the Maquis? Their refusal to give up star systems to the Cardassians and trying to drive the Federation into another war, I think you could consider that greedy. I'm sure there are other examples of people in the Federation only interested in exploitation.
Not sure where you're getting greed
from that. The Maquis weren't interested in gaining
new territory so much as they wanted to retain
the territory they'd already claimed for themselves before the treaty gave it away. Their methods weren't legal by any stretch of the imagination, but I don't recall them demanding more territory or resources than they had previously. Their goal was restoration of the status quo, nothing more.