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Still, the cargo you obtain from piracy is not likely to make you rich (unless you go after lo-temp diamonds) plus the amount of cargo you can carry in your pirate ship is limited because I can't see large cargo carriers as pirate vessels.…
Piracy only makes sense if it is the only way for the pirate to get something the pirate would otherwise not get.
This can be because the pirate has no access to the markets where those goods are traded or because the goods are restricted.
And even if the would be pirate has no access to certain markets or there are restricted goods, becoming a pirate makes only sense if the risk vs. reward vs. effort is balanced.
Why would anybody sane become a pirate if earning more money is easier, less risky and quicker by doing something legal?
The problem of piracy and crime in this game is, there is no reason for piracy.
Almost all commodities are easily accessible. Every CMDR has easy access to all markets and there are plenty methods of making credits without having to become a criminal.
The only reason to engage in criminal activities in this game is because some player consider doing those things fun - nothing wrong with that. It just doesn't help if it affects/reduces the fun of other players.
In my opinion things would dramatically change if there where situations in the game where becoming a criminal is not only a valid choice but maybe even the only choice.
This would require activities that are legal having bad consequences in some cases - getting cut off from markets and other profitable activities.
It would require activities that result in extreme profits, but that some or a lot of players can do because they are not allowed to.
And it would require ships, ship maintenance and modules to be extremely expensive for higher tier ships.
To be honest, I have no idea how this could be implemented without everybody getting angry about it.
TL;DR: The economy and the basic design of the game doesn't support the concept of piracy.