Fighting can also be another activity to try, or to live on in 2742. It can be either legal, personal, illegal or a military service. Fighting can be done in different ways, like taking assassination contracts to take down a pirate ship, or on the other side take down a normal or important ship; Both options offer lots of credits, and materials sometimes, as well as increasing a lot your reputation, from both sides. If you don't like contracts and/or missions you can apply to join the FSLEA, a special Federal space law enforcement, which is the military, and protect the system.
They are usually a usually legal activity, done by contracts which sets you and your combat ship, usually, to a take down mission for a faction or controlling power, to eliminate a specific target. Usually these contracts require you to find and hunt down a target ship or person, which has a bounty to collect for you. This activity can pay very well, as well as increase your rep.
The FSLEA (short for: Federal Space Law Enforcement Administration) is the security force keeping the system safe, after the Martian war. Joining the FSLEA gives you big advantage in pay, as higher ranks can get you to a pay of even 100,000 CR a day. As you work for the FSLEA you also gain LegalRep.
Pirating is illegal, but sure it is a way to make fast and easy money, most of the times. A pirate can make a living hunting vulnerable ships and getting their cargo, or if the pirate has enough power even have a pirate faction from where they make money from. Pirating is dangerous anyhow you do it, and does give you IllegalRep, but if done right can indeed increase your cash income overall.
Fighting can be both a legitimate and illegal activity, but sure it does offer great amounts of cash, if done correctly.