Do not compare the trader and gamblers i know and we all knows the difference between of them, same has have risk, but trading is a serous job to earn profits in the clean way, not unlike for the gambling is not the source of earning for is only the game of fears.
Gambling can be a source of income for those that play games that are not only about luck but about skill as well, sports betting is probably the most common way in which professional gamblers can make money, but you are right we cannot compare trading with gambling since in trading you can pick the market conditions in which you will participate while that is impossible with gambling.