The English language is poor with regards gambling because it uses one word "gambling" for two very different types of gambling activity.
The two types of gambling are -
games of skill
games of chance
The outcome of a game of skill can be affected by the use of the player's skills, e.g. poker, blackjack, horse race betting etc. - and trading.
The outcome of a game of chance cannot be affected by the player's skills, e.g. lottery, roulette, raffles etc.
So trading is gambling only if you accept it is a game of skill and not a game of chance. Whether you use your skills or whether you have any skills, or use them well or badly or whether you wish to win big or small, sooner or later, it doesn't matter, its still a game of skill. And so is business. So trading is a business as well.