This is a very hard question to answer. I think a trader becomes a gambler when he lets his greed gets the better off him. He doesn't know what is happening to him but the ultimate result is loss. Nobody can deny it. I know it is hard to control your greed while trading but for your own betterment, you need to control it.
We are all gamblers unless shares are owned for the betterment of the company, collect dividend and vote.