After being a -10 pirate for 2 years I will say you can make good ISK, but there is risk.
If your in a gang of BS, you go out on a roam throughout low sec, maybe gate camp a little and get a few kills, you split the loot between whoever was on an op. But if even one of you loses a ship all the profit from that op is gone because all of the loot goes to the fella who lost his shiney tech 2 fitted battleship.
So you can make isk, but if you lose anything any possible profit is wiped away.
Doing highsec wars atm after grinding up my security status to -1.6, you can make some very good isk targeting mission runners and carebears in general. If your stealthy enough you can capture their Golems and their Navy Raven's in missions to ransom them depending on their setup. Or you can pop them and take the risk of popping the loot as well. If they keep their faction/tech 2 ships docked just camp them in and kill as many of their ships as possible, harrass them as much as possible and then ask them to give ISK to stop the war.