Paying does not equal buying. If I lease a car, you can still steal it. If I rent a car, you can steal it.

If I subscribe to a daily newspaper, you can steal it off my driveway in which case you steal from me and not the publisher because I never owned the content. If you sell my newspaper then you've stolen from the publisher even though I paid the publisher for that printed copy.

It's really not that hard. Original pirates could steal from dozens of merchants, share holders, and sailors in various ways and degrees, monies paid to monies earned, to monies owed, to monies potentially gained, by seizing the cargo of one vessel.