yeah... Reading this, pirates really just don't make any sense in Starsector
they are funded by nothing. And it's impossible for them to actually make more gains than losses considering everything in Starsector is relatively well guarded in comparison to the quality of fleets pirates deploy
additionally there are major military entities that if they could, would just decimate pirates considering they are allied with whatever stuff said pirates are attempting to destroy
Thulians get sponsored by one gen or the other to raid their fellow gens.
Kapteyn pirates are in agreement with the Laicaille Habitat and don't raid them.
Donn is used as recruitment (or banishing) grounds for marines by TT.
While not outright stated anywhere, for all we know Macario could be intentionally enabling Askonian revolution on Umbra to continue as part of some convoluted plan.
Other pirate worlds are not described as some grand epicenters of outlaw activity, just some hellholes in the middle of nowhere that are either run by minor brigands or don't mind cooperating with their fleets on account of being too inconsequential for any major faction to bother.
The only other outlier is Kanta's Den, but that's an actual battle station, with a minefield layer, and war fleets on stand-by. It's likely that other factions don't have the resources to commit to a siege without exposing themselves for a strike by other major players.