To be honest, he's got a point, a null point.
As a civilian, you can become a mechanic, medic, firefighter, work different jobs such as trucking, heli tour guide, sell hotdogs and ice cream, go fishing. You also get different challenges such as money bag hunting, treasure hunting, DEA lost shipment, as a criminal you can steal vehicles and scrap them for a pay, rob stores, rob stores' safe, do burglary, mug/pickpocket people, move contraband in a plane... There's plenty of activities which you can do for money and score/experience, they just don't because it's easier to kill a fresh rank 1 cop in an armored 4 door car.