A trader is always a gambler, simply because the risk of ruin cannot be eliminated, regardless of how clever or exotic the strategy.
If I google "gambler" on internet it leads me to the conclusion that every decision in our life is a gamble. Never the outcome is guaranteed and there is always a risk of failure, damage or missed opportunities. Only death is not a gamble.
There are of course degrees of gambling. But then again the qualifications and abilities of the gambler can make gambling more risky or less risky.
Marriage is a gamble. Staying single is a gamble.
Taking a job is a gamble. Refusing a job is a gamble.
Having children is a gamble. Not having childrenis a gamble.
...
All these things can have a negative outcome although the "gambler" was expecting a positive result.
When I started to trade my expectation was to make money in the long term. As it did not happen from the first day, my (now ex-) wife send me for therapy as I was, according to her, apparently addicted to gambling. Most people who have no clue about trading and confuse learning to trade with an addiction. It was not addiction but determination to succeed. They don't understand probabilities and have no knowledge at all about statistics. They are convinced that you can never make money as most people fail.
After our divorce I proved that I was making consistently money while she went from a good situation (financially in our marriage) to a bad one (financially). My daily average income now is higher then her monthly income.
She was the one who took a gamble, and lost it.
The danger of a gamble depends on the understanding of the gambler what risk he takes and what the realistic expectations can be.