Doctors, enginnering etc provides their service in return for a reward.
Trader provides their time and risking their money, and get their Reward (which could be negative reward).
So it is almost equal.
Also whenever you participate, you are making the economy to move.
If everyone stays in cave plant own food, the economy going to go down pretty fast, for a start stock market and other business going to "lau sai" (in hokkien). As there are very little "kang tau" left.
by this theory, the highest traffic accident in malaysia actually adds on GDP to the nation. Because, it involves services: ambulance, insurance agent, ...