I consider trading as a professional activity. It requires analysis, research and others knowledges. Gambling you just require luck. But yes, maybe there is a thin line between then. It depends on how you do trading.
Yes I agree with you that there is no doubt about this that gambling is a professional activity, trading can be consider as profession, because in trading you need good study analysis and trading skill with previous experience, while in gambling you need just your luck and nothing else.