I pirate sometimes, but the credits are really not the main deal-- if there was no RP in pirating, I wouldn't do it. BORING.
The only point to pirating without RP would be showing you could outsmart traders with your ambushes, positioning, timing, teamwork, tactics, etc.
Too often it's just a pirate showing off their superior firepower to a transport (duh) or how much of a demanding a-hole you can be (count downs, ultimatums). If you're going to do that, you might as well be law enforcement. Thats how the po-po act when you're smuggling artifacts.
A pirate should have more flair, elán, Captain Jack Black in him/her.
You are calculating the cost/benefit of submitting to demands as if this were REAL MONEY. Its not. The only value to credits is how it furthers my RP-- that includes buying a ship and guns, but just so I can have a ship/loadout that matches the RP/affiliation I am representing.
An actual loss in credits might be a gain in RP.
One major gain is that if a pirate is coming at me like a homeless panhandler with no reason for his demands or countdowns other than he'll shoot me, I can refuse on principle unless he dances for his supper.
If he decides to give me some backstory, jokes, jibes or bluster and really inhabit his pirate role, I'll pay him. He usually shoots me first, but I'm still sticking to my guns and demanding RP. The result? A little bit more RP on the server.
If I give in, maybe its cheaper than replacing my cargo, but I've sold out. I let some no RP pirate hack win out.
I have enough panhandlers in my RL city without encouraging them online. At least make me laugh!