Call it what you like. But yeah it is gambling. Not gambling like slots or roulette or keno or craps or baccarat. Gambling like poker or maybe blackjack.
Here is my justification. Not all gambling is 100% chance. Some games have a skill element. If you watch poker tournaments on TV, at every high level game you will notice that 75% of the faces you see around the table were there last year. That is because skill can overcome "bad luck", at least in the long run. That's not to say that you can't occasionally take a bad beat in spite of being a very good player, but you know how to manage your money and manage your risk, and live to play another day. Does that sound familiar? It should, if you are a trader.
There are professional players who don't bother with tournament play because the odds/payoff suck except for the top half dozen players who know they are gonna make a pile of dough. Yes, professional players you have never heard of, playing in Nevada and the California poker rooms and underground or kitchen table games all over the country. And that is all that they do, is play poker, and some make a pretty decent living at it. And yet, even though it is their occupation, we call it gambling. The law calls it gambling. The IRS calls it gambling. You call it gambling.
Trading, even from a position of skill and experience, has risks, same as poker. You can get unlucky and take a bad beat, same as poker. If you are really good, you will make more than you lose, same as poker. If you are VERY good, you can make a fine living at it, same as poker. And you feed on the weak players, same as poker. Your skill matters, and though you can lose a lot in a day, you control your losses, and your wins are big enough or common enough to make up for the losses. Same as poker.
Some guys trade like they are at the race track or an OTB parlor. Nearly all will fail. So yeah you can trade like a track junkie. You can even trade like a slots addict if you like. But the smart trader plays like a smart poker player. He gambles, but with an edge. He takes way more than his fair share of the cookies from the table and leaves the weak players wondering what the hell just happened.
Doesn't matter if you do it for a living. Doesn't matter if you never or almost never have a losing day. Doesn't matter if at the end of the year you have improved your account by $300k or $300 or lost $50k. Doesn't matter if you are experienced and skilled and even have a degree or two. Doesn't matter what you choose to call it. It is gambling. Maybe with an edge, but it is gambling. And there is not a damn thing wrong with gambling, with an edge.